Thermostat Guards, Fire Station Protectors, Safety Technology International (STI), and more!

STI-6540: Mini Stopper II® without Horn Flush Mount, replaced with STI 13010FR


DISCONTINUED: Mini Stopper II® without Horn Flush Mount
STI-6540. NEW PART IS: 13010FR

This unique and patented device has helped stop false fire alarms around the world for over 30 years, without restricting legitimate alarms.

STI-6540 consists of a clear, tamperproof, super tough polycarbonate cover and frame that fits over manual pull stations. Additional models are available with a built-in warning horn that sounds when the cover is lifted to gain access to the pull station (see STI-6600). The STI-6540 offers excellent protection against physical damage (both accidental and intentional).


  • The cover is UV-stabilized.

  • Three-year guarantee against breakage of polycarbonate in normal use.

  • Proven effective for more than two decades.

  • STI-6540 is for flush mount pull stations (surface - see STU-6545).

  • UL Listed to U.S. and Canadian safety standards.

  • Typical working properties of polycarbonate are -40° to 250°F (-40° to 121°C).

  • Fits virtually all manual pull stations (see Technical Data Sheet for dimensions).

  • ADA Compliant.