The Rolleiflex 3.5 B (type K4B) is a twin-lens reflex camera produced by Franke & Heidecke from 1954 to 1956, with approximately 94,000 units manufactured. It features a Synchro-Compur MX CR00 leaf shutter with speeds from 1 to 1/500 sec. and B, and a Heidosmat 1:2.8 f=75mm coated viewing lens. This model introduced an Exposure Value Scale (EVS) for exposure adjustments and a switch to overrule the Double Exposure Prevention. It also includes a memo disc on the focus knob and allows for the use of a Rolleifix tripod attachment. The camera weighs 980 grams and has dimensions of 99 x 96 x 146 mm.