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STI KIT-M10271-BZA

STI Blue Unnotched Replacement Shell for Stopper® Station series - ...
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STI KIT-M06540-CY

STI Yellow Replacement Housing for Universal Stopper® series - Cust...
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STI KIT-M06540-CG

STI Green Replacement Housing for Universal Stopper® series - Custo...
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STI KIT-M06540-CB

STI Blue Replacement Housing for Universal Stopper® series - Custom...
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STI KIT-GLR-K2

STI KIT-GLR-K2 Global ReSet Key 2-Pack
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STI KIT-AP2100-YZA

STI Yellow Notched Replacement Shell for Stopper® Station series - ...
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$41.36 $31.99 Save $9.37

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STI KIT-AP2100-Y

STI Yellow Notched Replacement Shell for Stopper® Station series
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STI KIT-AP2100-RZA

STI Red Notched Replacement Shell for Stopper® Station series - Cus...
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STI KIT-AP2100-BZA

STI Blue Notched Replacement Shell for Stopper® Station series - Cu...

Blue notched shell replacement for Stopper® Station HID systems
Usually Ships in 2-3 Weeks Free shipping over $499

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STI KIT-316

STI KIT-316 Louvers for STI-3100 Conduit Spacer
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STI GLR441EX-EN

STI GLR441EX-EN Global ReSet Push Button Credential
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$175.08 $135.99 Save $39.09

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STI EP242410-O4

STI EnviroArmour® Polycarbonate, Power Distribution - Opaque
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$1,338.21 $1,017.99 Save $320.22

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STI EP242410-O3

STI EnviroArmour® Polycarbonate with NEMA 3R Filter Fan - Opaque
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$1,596.71 $1,118.99 Save $477.72

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STI EP242410-O2

STI EP242410-O2 EnviroArmour Polycarbonate Lock/Strike with AC
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$6,040.56 $4,238.99 Save $1,801.57

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STI EP201608-O3

STI EnviroArmour® Polycarbonate with NEMA 3R Filter Fan - Opaque
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STI EP161409-O3

STI EnviroArmour® Polycarbonate with NEMA 3R Filter Fan - Opaque
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STI EM362408

STI EM362408 Metal Protective Cabinet Lock/Strike
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$1,269.00 $891.99 Save $377.01

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STI EM1212DOC-U

STI System Record Documents Enclosure, Metal, USB Storage, Thumb Lo...
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$163.33 $111.99 Save $51.34

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STI EF181610-W2

STI EnviroArmour® Fiberglass with A/C and Heat - Window
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$5,978.40 $4,244.99 Save $1,733.41

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About STI

Safety Technology International, Inc. (STI), headquartered in Waterford, Michigan since 1977, manufactures the industry's broadest catalog of protective covers and shields for life-safety and security devices. STI covers are specified wherever vandalism, accidental activation, weather exposure, or tamper risk threatens device reliability — with the Stopper II and Stopper III lines alone covering virtually every fire alarm pull station and manual call point in the North American commercial market.

The product catalog is organized around five primary application areas: fire alarm protection (Stopper II without horn, Stopper III with integrated tamper-warning horn, specialized covers for duct detectors and smoke detectors), HVAC and thermostat protection (clear universal covers preventing occupant adjustment), security device protection (exit-button shields, emergency call-box enclosures, camera anti-vandalism cages), outdoor weatherproofing (weatherproof cabinet enclosures for outdoor-mounted devices), and ADA-compliant wayfinding (emergency call covers with integrated visual signage meeting ADA Section 4.31 requirements).

STI covers are engineered from thermoformed clear polycarbonate — the material used in ballistic shields and riot helmets — which provides impact resistance 250x greater than standard glass or acrylic while remaining fully transparent for visibility. Tamper-warning horn models add a loud piezo alarm that sounds when the cover is lifted, deterring vandalism attempts and alerting facility operators to tampering events.

STI Product Families

Every major STI product line — pick the family that matches the deployment.

Stopper II Fire Alarm Covers

Clear polycarbonate covers for manual fire pull stations — prevents accidental activation and vandalism without blocking legitimate emergency use.

Stopper III with Tamper Horn

Fire alarm covers with integrated piezo tamper-warning horn — sounds when cover is lifted, deterring vandalism in schools and public spaces.

Thermostat & HVAC Covers

Universal clear covers for thermostats, humidistats, and HVAC sensors — prevents occupant adjustment in healthcare, hospitality, and commercial.

Exit Button Protective Shields

Clear shields over emergency exit buttons — prevents accidental or malicious activation in commercial and institutional access control.

Emergency Call Box Covers

ADA-compliant call-box covers with integrated signage — protects emergency communication devices in parking garages, stairwells, campus grounds.

Weatherproof Cabinet Enclosures

Outdoor-rated enclosures for protecting fire panels, access control, and security devices from weather, UV, and moisture.

Camera Anti-Vandalism Cages

Stainless steel and polycarbonate cages protecting IP and analog security cameras in high-vandalism public spaces.

Electrical Boxes & Enclosures

Junction boxes, conduit fittings, and protective enclosures for life-safety and security device wiring.

Featured STI Products

A sample of the high-performance STI catalog.

STI EnviroArmour® Fiberglass Enclosure with Solid Door, AC and Heat

$5,953.99

STI EM362408A Metal Protective Cabinet with AC/Heater

$3,898.99

STI EnviroArmour® Polycarbonate with A/C and Heat - Tinted

$3,775.99

STI EN483612 EnviroArmour Solid Fiberglass Enclosure

$2,766.99

Where STI Fits

STI fits every deployment where life-safety or security devices must remain operational but are at risk of vandalism, accidental activation, or weather damage. Primary applications include K-12 schools (Stopper III with tamper horn on every fire pull station to prevent false alarms), healthcare facilities (thermostat covers in psychiatric and pediatric units, emergency call covers throughout corridors), commercial office buildings (exit-button shields to prevent accidental door triggers), parking garages and transit (emergency call-box covers with ADA signage), outdoor installations (weatherproof cabinets for fire panels and access control), and retail/hospitality (thermostat covers preventing customer adjustment). STI is specified by fire protection consultants and life-safety integrators for virtually every institutional and commercial project in the North American market.

Why Choose STI

Industry-Standard Vandalism Prevention

Stopper II and Stopper III are the default specification for fire alarm pull station protection in K-12, healthcare, and public commercial buildings.

Tamper-Warning Horn Deterrence

Stopper III's integrated piezo tamper horn sounds at 95 dB when the cover is lifted — actively deters vandalism and alerts operators to attempted tampering.

Ballistic-Grade Polycarbonate

Thermoformed polycarbonate delivers 250x the impact resistance of glass or acrylic while remaining fully transparent for visibility and legitimate emergency use.

ADA-Compliant Emergency Signage

Emergency call-box covers ship with integrated ADA Section 4.31 compliant signage — raised text, high contrast, and required visual indicators.

STI Technology Stack

Named technologies that matter when you specify STI hardware.

Thermoformed Polycarbonate

Ballistic-grade thermoformed polycarbonate — 250x the impact resistance of glass or acrylic while maintaining full transparency for visibility.

Stopper III Tamper Horn

Integrated 95 dB piezo horn that sounds when the cover is lifted — active vandalism deterrence beyond simple physical protection.

Universal Mounting System

Flexible mounting system fits most North American fire pull station, thermostat, and exit-button form factors — one SKU covers multiple device brands.

ADA Section 4.31 Compliance

Emergency call-box covers ship with integrated ADA-compliant signage — raised 'EMERGENCY' text, high-contrast visual, tactile edges.

NEMA 4X Weatherproof Enclosures

Outdoor-rated weatherproof cabinets with NEMA 4X sealing — protect fire panels and access control from rain, UV, salt spray, and temperature extremes.

Low-Profile Mounting Depth

Most STI covers mount with less than 2 inches of depth projection — minimal visual and physical impact on the protected device.

Typical STI Deployments

Common facility types and the hardware spec that typically fits.

K-12 School District

Stopper III with tamper horn on every classroom fire pull station, STI thermostat covers in all occupied spaces, exit-button shields at every access-controlled door.

Hospital Psychiatric Unit

Thermostat and thermostat-sensor covers throughout patient areas, STI weatherproof cabinets for exterior life-safety panels, exit-button shields at egress points.

Parking Garage Emergency Communication

STI ADA-compliant call-box covers on every emergency phone, weatherproof cabinet for card reader electronics, anti-vandalism cage on garage-mounted IP cameras.

Commercial Office Building

Stopper II on fire pull stations at every exit, thermostat covers in shared conference rooms, STI weatherproof cabinet for outdoor fire control panel.

More STI Products

STI EnviroArmour® Polycarbonate, NEMA 3R Filter Fan, Filter Vent, P...

$1,291.99

STI EnviroArmour® Polycarbonate, NEMA 3R Filter Fan, Filter Vent, P...

$846.99

STI EP242410-T EnviroArmour Polycarbonate Enclosure

$634.99

STI EP242410-O EnviroArmour Polycarbonate Controller

$605.99

Frequently Asked Questions About STI

Common questions from integrators and end users evaluating STI for commercial projects.

Do STI Stopper covers prevent legitimate emergency use?

No. STI Stopper II and Stopper III covers are designed to deter vandalism and accidental activation, not block legitimate emergency use. The cover opens easily by any user who needs to activate the fire pull station, sound an alarm, or make an emergency call. The tamper horn on Stopper III provides audible deterrence but does not prevent emergency operation.

Will Stopper III's tamper horn go off every time someone lifts it?

Yes — that's the design intent. The piezo horn sounds at 95 dB for approximately 15-30 seconds when the cover is lifted, providing audible warning that the protected device is being accessed. For legitimate emergency use, the horn will sound as the user triggers the fire pull station or emergency button — which is acceptable because the fire alarm or emergency call will follow immediately.

Are STI covers ADA compliant for emergency communication?

STI emergency call-box covers are specifically engineered for ADA Section 4.31 compliance — integrated signage with raised 'EMERGENCY' text, high-contrast visual markings, and tactile edges meet accessible-communication requirements. For fire alarm covers, ADA compliance applies to the mounting height and operable-surface requirements of the pull station itself, not the cover.

Can I install STI covers over any brand of fire pull station?

Most STI covers use a universal mounting system that fits the majority of North American fire pull station form factors (Simplex, Notifier, Honeywell Silent Knight, Edwards EST, Fire-Lite, Gamewell FCI). For specific models that don't fit the universal mount, STI ships brand-specific mounting kits. Consult our engineers with the specific pull station model before ordering if you're uncertain.

Do STI weatherproof cabinets need additional weatherproofing?

STI NEMA 4X weatherproof cabinets are sealed enclosures that don't require additional weatherproofing for typical outdoor deployment. The NEMA 4X rating covers water jet ingress, dust, and corrosion resistance. For extreme environments (coastal salt spray, industrial chemical exposure, Arctic temperatures), verify the specific enclosure rating meets site requirements.

What's the difference between Stopper II and Stopper III?

Stopper II is the basic clear polycarbonate cover without tamper horn — it provides physical protection and visual deterrence at a lower price point. Stopper III adds an integrated 95 dB piezo tamper-warning horn that sounds when the cover is lifted — providing active audible deterrence that's particularly effective in K-12 schools and public commercial buildings where false alarm rates matter.

Related Buying Guides

Engineering guides to validate your design before you specify hardware.

Shop STI By Category

Browse the full catalog by form factor and deployment.

Covers & Protection Weatherproof Cabinets Electrical Boxes & Enclosures Exit Buttons

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