Stopper II clear polycarbonate cover with a warning horn English labelling for flush mounted manual pull stations

The ultimate deterrent against false alarms and vandalism.

The Stopper II is a world-renowned protective cover made of clear, heavy-duty polycarbonate. It is designed to retrofit over manual fire alarm pull stations to prevent both accidental damage and malicious false alarms. When the cover is lifted to access the alarm, a powerful integrated siren sounds immediately, drawing attention to the user before they can even trigger the building's main fire alarm system.

This cover is UL listed hence the equipment and its installation meets Canadian standards. It is also FM approved; the Factory Mutual Approvals is a group offering testing and certification services on products for commercial and industrial use. This piece of equipment is ideal for fire safety in public locations such as schools, hospitals, mills, etc.

STI™ product code: STI-1100

Stopper II® covers protect manual pull stations from impacts and help prevent false fire alarms without restricting legitimate alarms. The cover can easily be lifted and is connected to the frame by a metal cable. It was designed for indoors use only. Such an accessory requires a double action to trigger a fire alarm compared to a simple pull station which requires one sole move.

All labeling on the cover and instructions provided in the package are in English (PDF version available for download).

External dimensions:
Length 7 in x Height 10 in x Depth 3.5 in
(Length 17.8 cm x Height 25.4 cm x Depth 8.9 cm) 

Inner dimensions:
Length 5.5 in x Height 6 in x Depth 3.25 in
(Length 14 cm x Height 15.24 cm x Depth 8.25 cm) 

Polycarbonate thickness: 0.095 in (2.4 mm)

This cover fits most pull station models, mainly flush mounted ones.

Covers with French labeling are also available as prescribed by the Province of Quebec regulations (see item ECSTI1100FRE).

Key Benefits: Security and Effective Deterrence

This model is a high-priority safety addition for public spaces, schools, and high-traffic buildings:

• False Alarm Deterrence: The integrated piezo horn (95–105 dB) acts as a powerful psychological barrier. Pranksters are often scared off by the local alarm before pulling the fire station lever.

• Indestructible Construction: Molded from tough Lexan polycarbonate—the same material used in police riot shields—it is virtually unbreakable and protects against kicks, sports balls, or equipment collisions.

• Clear Emergency Instructions: This specific model features clear English silk-screened instructions: "In Case of Fire, Lift Cover and Pull Station."

• Full Visibility: The clear shield ensures that the fire alarm station remains completely visible and compliant with safety identification standards.

• Flush-Mount Design: Specifically designed for stations that are installed "flush" against the wall (recessed electrical boxes).

Technical Specifications

• Material: UV-stabilized polycarbonate (resistant to yellowing and impact).

• Local Alarm: Self-contained piezo horn (95 or 105 dB at 1 foot).

• Power Source: 120V AC with 9V DC Alkaline battery backup (battery included).

• Dimensions: Approximately 7.2" W x 10.2" H x 3.3" D (Standard Flush Mount size).

• Operating Temperature: -40°C to 49°C (-40°F to 120°F).

• Certifications: UL/cUL Listed and ADA Compliant.

Application Guide: Recommended Installation Zones

The Stopper II is essential in environments prone to tampering or physical impacts:

1. Educational Facilities: Schools and universities where false alarms are a recurring issue.

2. Public Arenas & Gyms: To prevent accidental activation by sports equipment or stray balls.

3. Hospitals & Nursing Homes: To avoid accidental triggers in busy corridors.

4. Public Transport Hubs: Where high foot traffic increases the risk of vandalism.

FAQ: Frequently Asked Questions

Does lifting the Stopper II cover trigger the building's fire department?

No. The Stopper II has its own independent, battery-powered alarm. The building's main fire alarm system is only triggered if the person proceeds to pull the lever on the actual station inside.

How do I stop the local alarm once the cover is opened?

Simply close the cover back into its frame. The alarm is deactivated by a magnetic or physical switch that resets when the shield is returned to its normal position.

Occupational Health and Safety (OHS) Expert Advice

• Maintenance: Always check the 9V battery during your monthly or annual fire safety inspections. If the battery dies, the local alarm will not sound, losing its deterrent effect.

• ADA Compliance: This flush-mount model is ADA compliant, meaning it does not protrude more than 4 inches from the wall, keeping walkways safe for the visually impaired.

• Cleaning Tip: Only use mild soap and water with a soft cloth. Avoid abrasive cleaners or chemicals that could scratch or fog the clear polycarbonate.

Polycarbonate properties:

Polycarbonate is a clear low flammability material highly resistant to impacts which features impressive mechanical and thermal properties, hence its use in so many fields. It is commonly used to manufacture safety eyewear, protective faceshield, law enforcement shield, optical lenses, thermal imaging and so many other vandal-proof items. The polycarbonate used for the fabrication of Stopper II® covers is UV-stabilized against degradation caused by the sun. 

Maintenance and life service:

Some basic practices should be adopted to maintain manual pull station covers. It is thus recommended to wash the cover with lukewarm water and a gentle soap; be aware that if one lifts the cover while cleaning, the alarm will go on until the cover is snapped back into place. The manufacturer strongly advises not to use steel pads since they scratch any surface they touch which will temper with the legibility of the label. It also is not recommended to use harsh soaps on the cover since polycarbonate doesn’t mix well at all with a wide array of acids and other chemical compounds. Indeed, these products will make your cover kind of melt. If the cover surface isn’t soft to the touch and bubbles appear, the cover has been corrupted and must be replaced.

As for its life service, the manufacturer asserts that his Stopper II® covers are durable; some have been in service for almost 20 years. Of course, the warning horn and battery should be inspected every 6 months to make sure they function, and the 9-Volt battery should be replaced yearly if need be.

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