This is what the constructor lists on their website : "Fully automatic slide projector for the 41 x 101 format with a stereo image from 2 fields of the RBT stereo slide frames: Available formats of the RBT stereo slide frames: 21 x 16 mm (half format, e.g. NIMSLO) / 23 x 19.5 mm (Realist) / 23 x 21.5 mm (square format, e.g. Realist) / 23 x 28 mm (Belplasca, FED) / 23 x 30 mm (RBT) / 23 x 31.5 mm (RBT) / 23 x 33 mm (RBT, full format). Main connection for alternating current 50 - 60 Hz, switchable to 110, 220 and 240 V. Interchangeable lenses and accessories. Lenses in focal lengths 55, 90, 150 and 180 mm and Vario lenses 70-120mm. Infrared remote control, crossfade control units, control units for continuous projection."