This is a high intensity cold light source using a Quartz Halogen Lamp. It is used in conjunction with all Microscopes, G & H Series Borescopes and Micro-Probes. It has to be purchased as a separate item for all Fiber Optic Ring Illuminators, FOI-1 Bifurcated Bundles, FOI-2,3,4,5 and 6 Light Guides. It has a variable intensity Control. The unit has an internal Fan System to assist in cooling and prolonging bulb life.