Philips 13-Watt 21 in. Linear T5 Fluorescent Tube Light Bulb Bright White (3000K) 546481 - The Home Depot
10 x 21" 13W T5 Fluorescent Tube 535 [3500k] Standard White (Bell 05411) - - Amazon.com
Lightwise LWL7W40-F13T5 21" Direct Replacement Led Tube, 7-Watt, White, 4000K, Retrofit 13W T5 Fluorescent Tube of your Uncder-Cabinet Lights 50% Energy Saving, Replace Directly Set of 3