STI (STI-1221C) Strobe Damage Stopper w/Open Bkbx w/Exte

The STI STI-1221C is a Strobe Damage Stopper — a clear, vandal-resistant polycarbonate cover for fire-alarm strobes with external mounting tabs, supplied with an open back box for retrofit applications. First, the installer mounts the open back box over the existing strobe. Then the dome cover snaps over the back box on a continuous hinge. As a result, the strobe stays fully visible and operational while gaining UV-stabilized impact protection.

What the STI STI-1221C is built for

Notification appliance strobes are frequent targets of accidental damage in gyms, schools, and high-traffic corridors. However, removing or relocating the strobe defeats the NFPA 72 coverage. Therefore, the STI-1221C cover protects the installed device without restricting operation or blocking the flash, satisfying both protection and visibility requirements.

Verified STI STI-1221C specifications

• Family: STI Strobe Damage Stopper (the strobe-only variant of the Horn/Strobe Damage Stopper line)
• Application: Designed for strobe units with external mounting tabs
• Spacer / mounting: Spacer C — open back for retrofit applications
• Material: Clear, thick, UV-stabilized polycarbonate
• Hinge: Continuous hinge for easy service access
• Mounting tabs: External mounting tabs (back box has external tabs vs. internal)
• Compliance: UL Listed to U.S. and Canadian safety standards; MEA Approved
• Operating range: Polycarbonate working properties -40° to 250°F (-40° to 121°C)
• Sound impact: Used on audible devices, this cover reduces sound output by 6 dB(A); for horn/strobe combinations, use the Horn/Strobe Damage Stopper line (e.g. STI-1210 series) instead
• Warranty: Lifetime guarantee against breakage in normal use

Where STI-1221C fits in the Damage Stopper family

The STI-122x series is for strobes only. Specifically, the C suffix means open back box with external mounting tabs (retrofit); D means enclosed back box; E means flush mount. Furthermore, the STI-1210 series adds horn coverage for combination horn/strobe appliances. As a result, ordering the wrong suffix or family yields a cover that doesn’t fit the appliance.

Application context

Gymnasiums, school corridors, locker rooms, and warehouse aisles are common installations. In addition, the open back box of the C variant makes it well-suited to retrofitting existing strobes without removing them from the wall. However, this cover is strobe-only — for combination horn/strobes, specify the STI-1210 series.

Need help selecting the right part or verifying compatibility? Our team supports thousands of commercial fire alarm installations every year. Call us at 1-888-557-0558 or email sales@lifesafetycom.com for application guidance, lead-time updates, or volume pricing.