Honeywell CG512A1009/C CG512A1009 Large Thermostat Guard with Inner Shelf to Prevent Tampering, White Fits all Honeywell and most other thermostats Clear plastic cover that resists yellowing Key lock with inner shelf to prevent tampering Protects unwanted changes to AC/Heating preferred settings Ultra clear acrylic resin cover and base resists the yellowing effects of chemicals and UV-light