The Eiko 41091 prefocus scientific lamp operates at 15 watts and 12 volts. It is clear, with a C-6 filament and a DC Bayonet base. Its initial output is 130 lumens an ANSI code of EI77Z. The bulb's expected life is 100 hours. This lamp is to be used in Hosobuchi, Opti-Quip and Zeiss Ikon-Voigtlander instruments.