The individual image frames were conventional black-and-white, silver-based photographic prints on tough, flexible opaque cards. Rather than being bound into a booklet, the cards were attached to a circular core, rather like a huge Rolodex. A reel typically held about 850 cards, giving a viewing time of about a minute.[3] The reel with cards attached had a total diameter of about ten inches (25 cm); the individual cards had dimensions of about 2 3⁄4" × 1 7⁄8" (7 cm × 4.75 cm).