Low voltage spot bulbs have a 2 pin push in connector. The pins are often quite sharp and do not have 'feet' at the end of each pin.

There are various types of low voltage spot bulbs. They are often called MR16, MR11 or MR8. These names refer to the diameter of the front of the lamp, in 8ths of an inch. MR means 'multifaceted reflector'.

Sometimes the different bulbs are referred to by the distance between the center of the electrical pins. GU5.3, or GU4 are the common sizes, which are 5.3mm and 4mm apart.

GU10 bulbs have a 2 pin connector with 'feet' at the bottom of each pin. The feet are used to lock the bulb into place when it is twisted in the lamp holder. Because of this fitting method they are sometimes called 'twist and lock' bulbs. GU10 bulbs all run at mains voltage.

There are a wide variety of energy saving options to choose from brand new LED models, to larger brighter compact fluorescent lamps.

Screw capped spot bulbs also run at mains voltage. They are available in a range of sizes with variety of different screw caps. They are used in surface mounted fittings, recessed downlights and outdoor lighting.

The name of the bulb is determined by the diameter of the reflector part of the bulb. 'R' bulbs are descibed in mm, e.g an R80 bulb has a diamater of 80mm. The less common Par bulbs are described in 8ths of an inch, e.g. a Par38 bulb is 38 x 8ths of an inch.

Spot light bulbs with any sort of Bayonet connected are fairly uncommon. They are only used in some quite rare light fittings.