The LED versions are designed to replace the traditional halogen MR16s while using a fraction of the energy to save you money on energy costs. LED MR16s also emit significantly less heat than halogen lamps. If you're trying to replace an MR lamp and aren't sure which size your need, simply measure the diameter of the bulb's face. MR16 bulbs are 16 eighths of an inch, or 2 inches in diameter. These LED MR16s have a GU5.3 base and are available in dimmable and non-dimmable options.