Offering the same brightness as fluorescent and LED tube lights, 2D bulbs are turned into more compact shapes, making them more convenient and easier to install. 2D lamps, also known as Double D bulbs are available with two different cap types: the GR8 or the GR10q. The easiest way to tell which type of cap your bulb has is to count the pins on its underside: if there are 2 pins, it is a GR8 connector, and if there are 4 pins, it is a GR10q. Like 2D bulbs, circular bulbs offer the same brightness as standard fluorescent tubes, but they are turned into more compact shapes, making them more convenient and easier to install. Circular bulbs are available in 2-pin and 4-pin versions, and are usually installed as part of integrated light fittings, or in inspection lamps and magnifiers.