Middle Atlantic .5INCHHX5.5INCHD Multi Shelf - MS-5.5

Middle Atlantic MS-5.5 Small Device Rack Mounting Shelf

Overview

The Middle Atlantic MS-5.5 is a half-rack-unit (0.5U) vented shelf designed for rack accessories and lightweight electronics that need a fixed mounting point without consuming a full 1U of rack space. At 19 inches wide and 5.5 inches of usable depth, the MS-5.5 (often searched as MS 5.5) fits standard EIA 19-inch racks and handles gear up to 30 lbs — enough for most small media converters, modems, wireless access point controllers, or auxiliary security devices. If you're integrating a Middle Atlantic rack system and need a low-profile shelf that doesn't waste vertical space, this is the unit to reach for.

Key Features

• 0.5U Height (0.5 in / 1.3 cm): At half a rack unit tall, this shelf adds a mounting surface without sacrificing the vertical real estate you'd lose with a 1U or 2U shelf. In a fully populated 12U or 16U rack, that difference matters — every unit counts when you're trying to fit an NVR, patch panel, switch, and ancillary gear into the same enclosure.
• 5.5-Inch Usable Depth: The full 5.5 inches (14 cm) of depth is usable — not nominal. Shallow enough to leave clearance behind the device for cabling, but deep enough for small form-factor electronics like modems, fiber converters, PoE injectors, or small industrial controllers. Pair it with a rack enclosure that has 12 inches or more of internal depth and you'll have no clearance issues.
• 30 lb (13.6 kg) Weight Capacity: The 30 lb rated capacity is intentionally conservative for a 0.5U shelf — it means you're not limited to featherweight gear. A small UPS controller module, a compact media gateway, or a stacked pair of managed PoE injectors all fall comfortably under that ceiling. Don't exceed the rating, but understand it gives you genuine flexibility.
• 19-Inch Standard Width: The 19-inch (48.3 cm) width is the global EIA/IEC standard for rack equipment. The MS-5.5 drops into any compliant 19-inch rack — from a 4-post open frame to a two-post relay rack or a wall-mount swing-out enclosure — without any adapter hardware.
• Two Mounting Points: The shelf mounts at two rack-ear contact points, keeping the installation simple and tool-accessible. Two-point attachment is the norm for lightweight shelves at this depth; it's faster to install and remove than four-point hardware when you're reconfiguring a rack mid-project.
• Black Powder-Coat Finish: The black finish matches Middle Atlantic's rack enclosure lineup and standard rack hardware aesthetics. In client-visible deployments — reception areas, small operations rooms, conference rooms with AV racks — finish consistency is a detail integrators notice even when end users don't.
• Single-Unit Packaging: Ships as a single shelf with no multi-pack overhead. Order exactly the quantity you need per rack — useful for projects with mixed shelf requirements across different rack positions.

Integration and Compatibility

The MS-5.5 is compatible with any EIA-standard 19-inch rack frame, including open-frame two-post and four-post racks, enclosed rack cabinets, and wall-mount enclosures. It is part of the broader Middle Atlantic rack accessory ecosystem, which means it pairs cleanly with Middle Atlantic's own enclosures without gap or alignment issues. For security integrators, common use cases include shelving a standalone NVR satellite device, a small network appliance, or a wireless bridge unit inside a rack that also carries a network video recorder and PoE switch stack. For AV and IT applications, it's equally at home supporting a small streaming encoder, a control processor, or a DSP unit. Verify internal rack depth before ordering — the shelf itself is 5.5 inches deep, but you need clearance behind the device for power and data cabling. Most enclosed racks with 18 inches or more of internal depth will have no issues.

What's in the Box

• 1x Middle Atlantic MS-5.5 rack shelf

Frequently Asked Questions

Q: What rack size does the MS-5.5 fit?

A: The MS-5.5 fits any standard EIA 19-inch rack — open-frame two-post, four-post, enclosed cabinets, and wall-mount enclosures. Width is 19 inches (48.3 cm).

Q: How much vertical space does the MS-5.5 occupy in the rack?

A: It occupies 0.5U — half a rack unit, or 0.5 inches (1.3 cm) of vertical space. This is one of the most space-efficient shelf form factors available for EIA racks.

Q: What is the maximum weight the MS-5.5 can support?

A: The rated weight capacity is 30 lbs (13.6 kg). This covers most small network appliances, modems, media converters, PoE injectors, and similar auxiliary devices.

Q: What is the usable depth of the MS-5.5 shelf?

A: The usable depth is 5.5 inches (14 cm). This is the actual surface depth available for your device — ensure you account for additional rear clearance needed for cabling behind the shelved device.

Q: How many rack mounting points does the MS-5.5 use?

A: The MS-5.5 uses 2 mounting points for rack attachment, keeping installation straightforward and compatible with standard rack strips.

Q: Can the MS-5.5 be used in a wall-mount rack enclosure?

A: Yes. Any EIA 19-inch-wide wall-mount enclosure with adequate internal depth will accept the MS-5.5. Confirm your enclosure's internal depth provides at least 5.5 inches of shelf clearance plus cabling room behind the device.

Marty Allison

The Middle Atlantic MS-5.5 is the shelf I spec when rack vertical space is genuinely constrained and the device going on it weighs under 30 lbs. At 0.5U tall and 5.5 inches deep, it's the right answer for auxiliary gear that doesn't warrant a full 1U shelf but still needs a fixed, stable surface in the rack — not a dangling cable tie or a zip-tied panel.

Technical Highlights:

• 0.5U Form Factor: Half a rack unit of consumed vertical space means you can place this shelf between two pieces of primary gear without disrupting your rack layout. On a 12U wall-mount enclosure where every unit is spoken for, this distinction between 0.5U and 1U is the difference between fitting your build or not.
• 30 lb Rated Capacity: 30 lbs (13.6 kg) gives meaningful headroom for a 0.5U shelf. Most small appliances — PoE injectors, fiber converters, compact media gateways — weigh 2–6 lbs. You're not close to the limit under normal use, which matters for long-term reliability in permanent installations.
• 5.5-Inch Usable Depth: The spec says usable depth, not nominal depth — all 5.5 inches (14 cm) of shelf surface are accessible. That's the right depth for compact devices; deeper shelves at 0.5U tend to be unstable for short-chassis gear without additional retention hardware.

Deployment Considerations:

• Two-point rack mounting is standard for this shelf class. Confirm your rack's rail spacing and thread type before ordering if you're working with a non-Middle Atlantic enclosure — most EIA 19-inch racks are compatible, but some offshore rack frames use non-standard hole spacing that can cause alignment issues.
• At 5.5 inches of depth, budget for cabling clearance behind the shelved device. In an enclosed rack with 18 inches of internal depth, you'll have plenty of room. In a shallow wall-mount enclosure at 12–14 inches internal depth, check your device's connector depth before placing the shelf at the rear of the rack position.

The MS-5.5 earns its place in security rack builds where a small satellite device — a standalone NVR management controller, a cellular failover modem, or a wireless bridge unit — needs a clean mounting point inside an otherwise structured rack. It's the right shelf for that exact job, and a poor fit if your device is deeper than 5.5 inches or heavier than 30 lbs.