GE F40/UT/ECO-2, 2pack, This is a 40 watt, glass, linear fluorescent with a bi-pin base. It provides 2600 lumens, and has a cool white (4100 Kelvin) color temperature. The bulb is 1-1/2" in diameter (T12) and the MOL: 48". It has a CRI of 89 and a rated life of 20,000 hours.