This rotary slide tray holds 100 2x2-inch slides and has a spill-proof tray that features numbered slots for convenient reference. It's compatible with a wide range of projectors other than Vivitar, including Sawyers, Keystone, Nikon, Ward's, Penny's, GAF, Argus, Minolta, Sears, Hanimex, Anscomatic and Focal 20 and 30 slide projectors.