Keeler Professional/Vista Streak Retinoscope bulb Quanity (1) 3.6v Halogen 35mm lenght Keeler Bulbs Accurate diagnosis depends upon a number of factors. Of these, top quality illumination ranks as one of the most important. Only excellent visualization allows you to use your diagnostic skills to the full. For this reason, we at Keeler have invested heavily in our bulb manufacturing facility at Barnsley. All Keeler instruments use genuine Halogen and Xenon technology, yielding a brighter, whiter illumination and a longer life. Look at the bottom of your bulb to identify if your instrument is: 2.8V (Dry cell battery) or 3.6V (Rechargeable battery)   Innovator, market leader, with a focus on the future When you buy a Keeler instrument - what are you buying? Almost a century of experience in optics! Keeler has been manufacturing ophthalmic instruments since 1917. We continue to lead the market with our innovative instruments. This has been achieved through our continuous program of customer involvement in the design process to ensure our instruments meet the rigorous demands of daily practice.