T5 Triphosphor 13w Fluorescent Tube 531.1mm at LampShopOnline.
Triphosphor fluorescent tube 13W T5 White light 51.6cm 4000K F13T5/840
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
5 Pack of 13W T5 525mm 21" Fluorescent Tubes Cool White 4000k G5 Cap Bell Lighting 05412 : Amazon.co.uk: Lighting
Fluorescent Tube 21 13W T5 930 from Osram | General Lamps Lighting Supplies
Satco S1907 13w T5 F13T5/WW Soft White 21 inch Preheat Fluorescent Tub – BulbAmerica