PLT-26W 841, 4 Pin GX24q-3, 26 Watt Triple Tube, Compact Fluorescent Light Bulb by Circle Pack of 6 Compact Fluorescent (CFL) Plug-In Light Bulbs 10,000 Hours of Lifetime 4100K Bright Cool White GX24Q-3 4-Pin Base Make sure the base precisely matches your fixtures socket as this lamp will only work with the specific external electronic ballast it is a designed for