I purchased the 2U-4 pin configuration which is a compact fluorescent bulb. There are only two bulbs with this configuration, but they are sufficiently bright for my small bathroom. The included bulbs are 13 watt 2700K, which means the bulb emits a slightly warmer yellow colored light. If you prefer more of a bluer cooler colored light you can always swap for a 4100K bulbs. Install was relatively easy, but I would recommend small screwdrivers with magnetic tips due to the lack of clearance behind the fixture. Also, make certain that you have about 20 on at least one side of the assembly in order to slide glass cover off when installing bulbs. Not sure why the CF unit is more expensive since the xenon bulbs seem to cost more.