PondH2o PLL 2G11 UV-C Germicidal Replacement Lamp 36 Watt 16.1 Inch (532mm) PLL Type H Quartz Glass Germicidal Replacement Lamp For best results replace bulb every 6 months or 8000 hours Length Does Not Include Pins (Standard Industry Specification) 36 Watt 16.1 Inch (409mm) 2G11 Base For Use in Pond Filters, Water Purifiers