Often referred to as 2D, DD double turn or butterfly light bulbs, These ultraviolet UV light bulbs are commonly used in bulkhead lights in service stations, public toilets, and nightclubs. The special blue colour makes it very difficult to see veins so inhibiting the use of intravenous drugs. Compact energy efficient light bulb for use in low profile luminaires. Fitted with a GR8 2-pin square push fit base. Not suitable for dimming. Blue colour appearance.