The 1615 miniature bulb is a 30 watt, 6 volt incandescent with a single contact prefocus base. Additional specifications include: S8 clear glass, C6 filament, 0.88 light center length, 2 inch overall length and a rated life of 250 hours.
This is a replacement bulb for Bell & Howell slide and filmstrip projectors such as: 35-775-A, 35-756.
