With this particular bulb you get a cool white light. The brightness of a light bulb is measured in lumen, which in this case is 800 lumen.
From Amazon
Bell 13w T5 Fluorescent tube 4000K 515mm excl pins CHECK LENGTH CAREFULLY
Lamps 2U Direct
13 watt Cool White T5 Under-Cabinet Fluorescent Tube
swiftelectrical
Bell 13W T5 Halophosphor Mini Tube - 4000K, 525MM