The Sylvania ERD "2-pack" Projector Lamp is designed for use in slide projectors, specifically to fit various brands like Universal, Beseler, and Bell + Howell. This miniature projection bulb has a power of 35w and operates at 14v voltage, making it ideal for projecting slide filmstrips in a variety of settings. The pack includes two projector lamps, ensuring you have a replacement on hand when needed for your film photography or slide projection needs.