Use energy-efficient light bulbs if you're looking to cut as much energy costs as possible. On this light bulb you'll find a G23 socket.
From OnBuy
11w Osram Energy Saving Bulb DULUX S G23 2 Colour 830 Warm White (3000k)
LED Bulbs
Osram 11W Dulux CFL S 2 PIN Warm White - OS025759
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