STI Stopper II® with Horn and Spacer (Indoor/Outdoor - STI-1155

STI STI-1155 Stopper II Protective Cover with Horn and Spacer

Overview

The STI-1155 is a tamperproof polycarbonate protective cover for manual fire alarm pull stations, rated for both indoor and outdoor deployment. It combines physical damage prevention with a 9VDC piezo horn to deter false alarms while maintaining legitimate activation capability. UL listed for U.S. and Canadian safety standards, this cover has been proven effective for over 40 years in schools, hospitals, nursing homes, hotels, and public facilities where accidental or intentional false alarms represent a real operational cost.

Compatibility

The STI-1155 accommodates most standard manual pull station designs. The included spacer kit enables installation on both surface-mounted and recessed pull stations. For larger pull stations or ADA-compliant applications requiring additional clearance, the optional STI-3100 conduit spacer provides extended offset. The horn operates independently on 9VDC alkaline battery power (included), allowing standalone deployment without integration to a facility control panel.

Installation Notes

Indoor installations face no environmental constraints. Outdoor installations require weatherproofing—the STI-1155 features closed-cell gaskets rated for wet and humid conditions. Operating temperature range spans −40°F to 250°F (−40°C to 121°C), covering freezing climates and high-temperature industrial environments. Mount the cover directly over the pull station using the included hardware; gasket design prevents water ingress while preserving pull actuation force. Verify pull station activation does not exceed cover opening resistance before final commissioning.

What's in the Box

• 1x Stopper II polycarbonate protective cover and frame
• 1x Piezo horn module
• 1x Spacer kit
• 1x 9V DC alkaline battery
• Installation hardware and documentation