combining the same great quality light and compact design, while removing the need for a transformer. GU10 bulbs are available in three main formats; halogen, CFL (Compact Fluorescent Lamp) and LED (Light Emitting Diode).Halogen bulbs are a more recent version of the traditional incandescent bulb. Due to ease of manufacture and availability they are by far the cheapest of the three technologies. However, they are also the most expensive to run and have the shortest life expectency, which means the overall cost of the bulb ends up working out many times more than the initial price paid.CFLs are a compact version of the fluorescent tubes commonly found in offices. They are more expensive to purchase than halogen bulbs, but benefit from a lower running cost. While manufacturers have overcome the size limitations associated with creating a CFL-compatible GU10 Bulb, they still hold a considerable number of drawbacks. The most common criticisms levied against this type of bulb is that it produces a "cold" light, it loses much of its brightness overtime and that it takes a long time to reach full brightness after being switched on.Of the three bulbs, CFLs are also probably the most environmentally controversial. Fluorescent based lighting requires a small amount of Mercury vapour as a part of its operation. While the amount contained in a CFL is only about enough to cover the nib of a ball point pen, even a microscopic amount of mercury can cause massive environmental damage. This makes their disposal difficult and potentially dangerous.LED GU10 are the newest technology on the market and for this reason are also the most expensive. However, LED GU10s recoup most of this initial cost by lowering lighting bills and reducing the number of replacements required. LEDs also offer a number of other advantages as well, including lower operational temperatures and a greater option of colours.Although the price of LED GU10s are still high, this price is predicted to come down very soon. When that happens, LEDs will become the most popular lighting format available.Most existing transformers used by MR16 spotlights are incompatible with LED technology. For this reason many customers find it simpler and cheaper to upgrade their lighting system to mains voltage LED GU10 Bulbs.