RAY OPTICS AND COLOUR MIXING BOX (0533) Sheet Metal box with 12V, 10W Festoon type axially straight filament lamp. The body is fitted with a cartridge for holding 4 types of slits - single, double, triple and wide slots for quick adjustment to get the desired ray/beam type and with colour filters. Also included is a convex cylindrical collimating lens for adjusting the beam type to obtain long clear tracks parallel, converging or diverging in nature. Qty :