BELL 13W 4-Pin 840 Cool White : Amazon.co.uk: Lighting
Bell 13W T5 Fluorescent Tube in 4000k Cool White
LUXRITE 32-Watt Equiv. 4 ft. Linear Tube T8 LED Light Bulb Ballast and Ballast Bypass Compatible 13W 4000K Cool White (4-Pack) LR34192-4PK - The Home Depot