We stock all sizes of MR bulbs, from the most common MR16 to the less common MRs like the M-R18. Our MR18 bulbs have GX7.9 2 pin bases bulb and have a 3,400K color temperature, giving it a crisp white light. The MR18 differs from the MR-16 with regard to the bulb’s diameter. The ‘18’ and ‘16’ correspond to 18/8 of an inch and 16/8 of an inch, meaning that an MR-18 is 2.25in in diameter. MR18 bulbs are used in a wide array of applications from medical equipment to projectors, so if you have lighting needs in these fields the MR18 may be for you. If you need this specialty bulb or other specialty MR bulbs we likely have the one you need and at a great prices too!