iSpring 123Filter UVT11A - 11-Watts 110-Volt Transformer Ballast with Smart Flow Sensor Switch Smart Flow Sensor Switch automatically powers on/off UV light by water flow Includes Transformer and Flow Sensor Switch. It works with 11W UV lamp The kit is part of iSpring UVF11A but can also be used to add Smart Flow Sensor to other 11w UV filters Resolves the issue that water gets heat up by UV light. Extends UV lamp life. Smart Flow Sensor Switch powers on/off automatically by water flow Complete upgrade Kit, can replace older UV transformer that stays on Save energy, reduce heat hazard, extend UV bulb life 1/4" quick fitting, 1 GPM, 11 watts, 110v AC (220v model UVT11B) 30 day money back and 1 year manufacturer warranty