Sterilight S36RL 39 watt lamp with 4 staggered pins Suits all Sterilight S12Q-PA UV units. 2 x 10 inch x 4 1/2 inch Alpine Pure Gradient Density prefilters. The 20 micron cartridge is first followed by the 1 micron second. Third is the Granulated Activated Carbon cartridge. When doing the yearly service please remember to remove and clean the Quartz tube to enable the UV lamp to penetrate through the Quartz Tube to sterilize to water. To reset the ballast, replace the lamp but do not turn the power supply on, press the small black button on the end of the ballast and hold in while you turn on the power. Keep holding button in for up to 20 seconds until RESET shows on the LED screen then 365 will show when the button is released.