LEDVANCE's fluorescent light requires two bulbs. This model should be used indoors and the bulbs should be no stronger than 60W.
From Lighting-Direct
29.49
Lyco
Ledvance SubMARINE 2 x 16W Cool White LED Weatherproof Batten - 4ft Twin
Conrad Electronic
LEDVANCE SUBMARINE (EU) Wet room diffusor LED (monochrome) G13 34 W Neutral white Grey