Honeywell Metal Large Guard Thermostat Guards Unique double-wall construction provides extra measure of tamper-resistance. Tamper-resistant lock; key cannot be removed unless in locked position Constructed of opaque polystyrene Vents in guard base allow airflow for optimum thermostat performance Includes opaque polystyrene wallplate, ring base, guard cover, tumbler lock, two keys and optional Honeywell logo insert.