Helios-44M-4 58 mm f / 2 lens is a high-apertured, normal lens with a fixed focal length for cameras with an M42 connection thread. Specifications: Format: 35mm mirror Type: Constant focal length (fixed) Focus: Manual Focus System: M42 Optical design: 6 elements in 4 groups Focal length: 58mm Aperture: f / 2.0 - f / 16 Petal diaphragm: 6 Diameter of filter thread: 52mm Weight: 300g Length: 42mm Year of production: 1991 Product condition. Good condition. There are no scratches or fungi on the lenses. There are micro dust inside. The mechanics are working properly.