The SpeedLight Jr. Germicidal Light System from Filtration Manufacturing uses a four pin design and an 18 watt 14″ Ultra Violet bulb. Powerful magnets attach the bulb so it stays put using the U bracket that came with the system or to the delta plate on the coil. No Screws required. The U bracket allows you to install the bulb inside the blower section of your furnace or air handler. The magnetic base of the bulb allows you to drill a hole for the bulb to pass through to attach to sheet metal. The Speedlight Jr is a breeze to install. 1 year warranty .