The "Touch-Free" advantage eliminates a major source of cross-contamination, Encourages thorough healthy hand washing. with "Surround Sensor" Technology specializes in cost control. It immediately reduces waste by eliminating unnecessary and unattended water flow. -Provides the user water onLY when needed, resulting in reduced water usage and associated costs. -Save up to 70% on water cost associated with faucet usage. -Breakthrough "surround sensor" technology senses user from any angle. Patented cam gear technology controls water flow and eliminates sticking solenoid valves that cause dripping. All mechanical and electrical components are contained in one covered housing for easy installation. The Auto Faucet requires 4 D-Cell batteries.