STI will be closed from December 24th – 26th and December 31st – January 2nd. Normal business hours will resume on January 5th, 2026.
STI will be closed from December 24th – 26th and December 31st – January 2nd. Normal business hours will resume on January 5th, 2026.

The Thermostat Protector with key lock helps protect thermostat and energy sensors. The polycarbonate cover mounts directly over the unit to prevent unwanted access yet allows authorized use with the provided key. Designed with holes in the frame to allow air to circulate freely (for proper operation of protected thermostats) yet an inner wall prevents tampering with dials and levers. It is quick and easy to install.
More videos

STI manufactures high-quality protective covers, cages, alarms, and custom push buttons that safeguard essential life-safety and security devices. Trusted worldwide, STI’s innovative product line helps prevent vandalism, false alarms, and accidental damage, ensuring long-lasting protection and reliable performance for the equipment that protects people and property.

Learn how to easily install the Stopper II® with spacer, the industry’s most trusted protective cover for manual pull stations. For over 40 years, this patented design has helped prevent false fire alarms without restricting legitimate activation. Ideal for schools, hospitals, and public buildings needing reliable alarm protection.

The Steel Web Stopper® high-profile wire guard (STI-9610) protects smoke detectors from vandalism and accidental impact. Constructed of heavy-duty steel wire with a corrosion-resistant coating, this surface-mount design ensures reliability in high-traffic or exposed environments like warehouses, gyms, and commercial buildings.