Speakman's Sensorflo 4" lavatory faucet was designed for maximum vandal resistance and easy maintenance. All components are housed above the counter, inside the faucet housing. The faucets are battery or AC powered and include hot and cold mechanical mixing valves. They are pre-assembled for simple installation. Hot and cold check valves and filters are standard. The aerator on the faucets is fully recessed and vandal resistant. A lengthened spout reduces splashing. Automatic shut-off after 60 seconds of continuous use prevents flooding.Speakman.