Philips 13-Watt 21 in. Linear T5 Fluorescent Tube Light Bulb Cool White (4100K) 546499 - The Home Depot
Connectable T5 13W LED link light, opaque diffuser, cool white and warm white light
4 Pack T5 21 Inch LED F13T5CW LED Replacement Bulb F13T5 LED 9 Watts 920 Lumens Cool White 4100k F13 T5 13 Watt Bulb - - 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 - - Amazon.com
4 Pack T5 21 Inch LED F13T5CW LED Replacement Bulb F13T5 LED 9 Watts 920 Lumens Cool White 4100k F13 T5 13 Watt Bulb - - Amazon.com
Satco 13W 46" 5000K Single or Double-Ended T5 LED Bulb, Ballast Bypass | 13T5/LED/46-850/BP/HE/SE-DE | Bulbs.com