CNZ 55 Watts 2G11 Base UV-C Germicidal Ultraviolet Light Bulb QTY 2 UV Output @ optimum 254nm= 170 W/cm2 2G11 Base Glass/Quartz Bulb length (not including plastic end) for 55 watt= 20 (50.8 cm); Bulb Length WITH plastic insert, NOT including pins; 21" (53.3 cm) Plastic Insert 1-3/4 wide