Sunlite 30010-su f20t12/cw 20w fluorescent t12 bulb, medium bi-pin, cool white the fluorescent 20 watt 4,100k cool white t12 straight tube features a medium bi-pin base, provides a light output of 1,150 lumens at a color rendering index (cri) of 62 and can last an average of 8,000 hours.