Resideo TG512A1009 is a large clear plastic thermostat guard measuring 5-7/8 by 8-3/8 inches, designed to protect wall-mounted thermostats from damage and unauthorized adjustments. The guard functions by securely enclosing the thermostat while maintaining full visibility of temperature settings and display. It is commonly used with residential and commercial HVAC thermostats installed in offices, schools, retail spaces, healthcare facilities, and public buildings. Key benefits include enhanced thermostat protection, prevention of tampering, improved temperature consistency, reduced energy misuse, durable clear construction, easy installation, and long-term reliability in high-traffic HVAC environments.