CR P2 lithium battery installed; Battery Life: 4 years assuming 4,000 flushes per month Touch free operation helps keep the restroom clean and hygienic Pressure Compensation feature maintains accurate flush volume regardless of inlet water pressure Self cleaning piston significantly reduces clogging and prevents valve run on Integral wiper spring cleans the refill orifice with every flush for extraordinary reliability No Routine Maintenance no diaphragms to replace; no filters to clean Selectronic Proximity System with programmable sensor allows for easy adjustment and customization State of the Art Electronics prevent ghost flushing Fully Mechanical Manual Override Button can flush the valve without power Fail Safe: Valve automatically closes upon loss of power or water pressure and does not need to be reset