MGC offers a range of Keeler halogen lamps/bulbs for direct ophthalmoscopes. All Keeler instruments use genuine Halogen and Xenon technology, yielding a brighter, whiter illumination and a longer life. All lamps are supplied in packs of two for convenience.
You can check the bottom of your lamp to identify if your instrument is 2.8V Dry cell battery indicated with a blue colour or 3.6V rechargeable battery indicated with a red colour.
More information can be found here