Series USG-P Plastic Under Sink Guardian thermostatic mixing valve automatically blends hot and coldfor safe delivery from hot water faucet. If cold fails or is shut off, flow to hot water faucet ceases, eliminating potential for scalding. Valve maintains 3 F. temperature in range adjustable from 60 to 120 F. Built-in check valves prevent cross flow of hot water into cold water supply. Double throttling design controls hot and cold water supply to mixed outlet. Locking safety cap prevents accidental temperature adjustment.