This is the small 12V bulb that illuminates the filtration scale readouts on LPL 7700 series (Saunders/LPL and Omega/LPL 670XL) Dichroic Color and VCCE enlargers. Some disassembly of the lamphouse is required in order to access and replace the lamp - refer to the enlarger manual for instructions. For full replacement, 3 lamps are used in the Color lamphouse and 2 are used in the VCCE lamphouse.