Philips 13-Watt 21 in. Linear T5 Fluorescent Tube Light Bulb Cool White (4100K)For effective residential and commercial lighting, select the Philips 13 Watt 12 in. T5 Cool White Linear Fluorescent Light Bulb (F13T5 CW 4100K). It produces cool, white light and can last up to three years. The T5 linear fluorescent bulb has a medium, bi pin base. It is meant for indoor use. Brightness: 820 Lumens Estimated yearly energy cost: $1. 57 (based on 3 hours day, 11c kWh, cost depend on rates and use) Lasts up to 6. 8 years (based on 3