Triangle Bulbs T30031 (10 pack) - F13T5/WW, 13 Watt, T5, 3000K Warm White, 21" Straight Fluorescent Tube Light Bulb, 10 Pack (F13T5/WW - 21 inches Long) F13T5/WW 13-Watt T5 21" Maximum Overall Length 20,000 Average Life Hours