The Beseler 90mm f/4.5 Enlarging Lens is designed to work with 6 x 7cm format negatives.This enlarging lens for 6x7cm film comes with optical glass elements that are coated and color correctedIt has an F-stop range from f/4.5 to f/22The iris diaphragm of this enlarging lens features click stopsThis enlarging lens consists of a 39mm (Leica) mounting thread at its backThe Beseler 90mm f/4.5 Enlarging Lens comes with a lens cap and jam nut