Auto Faucet® SST sets the standard for reliability and user-friendly performance in automated faucet systems with patented Surround Sensor™ Technology. Touch-free activation eliminates cross-contamination to help reduce the spread of germs. Surround Sensor™ technology creates a 3'' omni-directional sensing zone guaranteeing activation every time. Patented ''dry'' cam-gear technology (solenoid valve free) ensures trouble-free operation to reduce maintenance. Long battery life - 400,000 cycles or three years (4 ''D'' batteries included). Optional AC power adapter available.