CHOOSING HALOGEN SPOTLIGHTS
The most common halogen spots are either low voltage push fit (GU4 or GU5.3) or mains voltage twist and lock (GU10) versions. Check out our most popular halogen spotlights below...
The GU10 has two studs at the bottom and has a twist-lock action to insert and remove from the fitting. This measures 50mm across the face of the bulb. It is a 240V mains halogen and is quite different from the 12V versions. You may wonder what the 10 in GU10 stands for - well, it means that there is a 10mm distance between the centres of the two studs.
The MR16 has 2 sharp pins on the bottom of the bulb that are simply pushed into the fitting, which is why this kind of bulb is commonly referred to as a 'push fit'. This is a 12V lamp which requires a transformer and is quite a bit larger than the MR11. It measures 50mm across the face of the bulb. The 5.3 in GU5.3 means that there is a distance of 5.3mm between the two pins.
The MR11 has 2 sharp pins on the bottom of the bulb as well and is also classed as a 'push fit' bulb. It is a 12V lamp which requires a transformer, but what makes it different from the the MR16 is its width, which measures 35mm across the face of the bulb. The 4 in GU4 means that there is a distance of 4mm between the two pins.