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.

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STI G3A125XT-EN

STI G3 Multipurpose Push Button with Shield No - G3A125XT-EN

12VDC momentary push button designed for request-to-exit and entry request switching in access control systems
- Operates on 12VDC momentary input, compatible with standard electric strike circuits.
- NC/NO/COM contact outputs support both normally-open and normally-closed locking logic.
- Shielded stainless steel enclosure protects contacts; 1/2" NPT entry fits standard conduit.
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$97.99

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STI STI-7531MED

STI MED Protective Cabinet, Polycarbonate with Wire Rack and Thumb ...

Polycarbonate protective cabinet with thumb lock for equipment security
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$391.96 $302.99 Save $88.97

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STI STI-4100EM

STI STI-4100EM Break Glass Stopper Large Emergency

Large break glass stopper for emergency egress and manual override
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$87.59 $67.99 Save $19.60

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STI STI-14020CB

STI Universal Stopper® Low Profile, with Horn, Flush, Custom Label
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STI STI-13220CK

STI Universal Stopper® with Horn, Surface Mount, Custom Label
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STI STI-13020CR

STI STI-13020CR Universal Stopper with Horn Flush Mount

Flush-mount stopper with horn for 24VDC intercom systems
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$136.73 $103.99 Save $32.74

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STI STI-13020CG

STI STI-13020CG Universal Stopper with Horn Flush Mount

Flush-mount door stopper with horn for access control systems
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STI STI-1250CR

STI Weather Stopper® without Horn Flush Mount, Custom Label

Flush mount 9VDC strike with weather sealing for exterior doors
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$108.86 $77.99 Save $30.87

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STI STI-1230CR

STI Stopper II® without Horn with Spacer, Custom Label
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STI STI-1150-FR

STI Stopper II® with Horn Flush Mount (Indoor/Outdoor Rated), Frenc...

Flush-mount horn with TCP/IP networking for indoor/outdoor alerts
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STI SS2301LD-EN

STI SS2301LD-EN Stopper Station White Turn to Reset
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$91.56 $69.99 Save $21.57

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STI SS2002ZA-EN

STI Stopper® Station - Red, Key to Reset (illuminated)
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STI RP-RF2-01

STI RP-RF2-01 ReSet Call Point Flush Mount Red
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STI NT-CA100-GZA

STI NoTouch® Cast Aluminum Switch, US Single-Gang, with Custom Gree...
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STI KIT-M10271-YZA

STI Yellow Unnotched Replacement Shell for Stopper® Station series ...

Yellow replacement shell for Stopper Station HID access control
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STI KIT-M10271-Y

STI Yellow Unnotched Replacement Shell for Stopper® Station series
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STI KIT-M10271-WZA

STI White Unnotched Replacement Shell for Stopper® Station series -...
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STI KIT-M10271-W

STI White Unnotched Replacement Shell for Stopper® Station series
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STI KIT-M10271-RZA

STI Red Unnotched Replacement Shell for Stopper® Station series - C...
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STI KIT-M10271-GZA

STI Green Unnotched Replacement Shell for Stopper® Station series -...
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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.

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

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STI products

About STI

STI Product Families

Featured STI Products

Where STI Fits

Why Choose STI

Industry-Standard Vandalism Prevention

Tamper-Warning Horn Deterrence

Ballistic-Grade Polycarbonate

ADA-Compliant Emergency Signage

STI Technology Stack

Thermoformed Polycarbonate

Stopper III Tamper Horn

Universal Mounting System

ADA Section 4.31 Compliance

NEMA 4X Weatherproof Enclosures

Low-Profile Mounting Depth

Typical STI Deployments

K-12 School District

Hospital Psychiatric Unit

Parking Garage Emergency Communication

Commercial Office Building

More STI Products

Frequently Asked Questions About STI

Do STI Stopper covers prevent legitimate emergency use?

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

Are STI covers ADA compliant for emergency communication?

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

Do STI weatherproof cabinets need additional weatherproofing?

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

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