Small Thermostat Protector Flush Mounted with Frangible Lock - 

To help stop vandalism, damage and tampering to thermostats, energy sensors and controllers. This protective cover is recommended for areas where abuse or tampering of thermostats is a problem. Holes in the frame allow air to circulate freely for proper operation of the protected device, but an interior wall prevents objects from entering inside. This unit has a key lock facility which prevents unauthorised entry, especially useful where thermostats are located in public areas.