The listing states "F-mount" due to Mercari's specifications, but it is actually an M-mount. This is a MS-OPTICS 28mm f/2 prime lens. I purchased it used from a camera store in Tokyo last year. Please be aware of the following: ⚠️ There is no original lens cap. (It was not included when I purchased it.) ⚠️ The focus knob is not the original. I lost the original during shooting and replaced it with a knob from a VND filter. ⚠️ There is a slight misalignment in the f-stop markings. This does not affect usability. ⚠️ The paint on the lettering is wearing off. The optical condition has some dust, but it shouldn't affect practical use. In my amateur opinion, there is no haze or fungus. The aperture and focus work without issue and have a good amount of torque. The only included accessories are those shown in the photos. If you have any other questions, please feel free to comment. I'm also willing to negotiate the price to some extent, so please let me know. Sold as-is, no returns. Compact design with high image quality. - Model Name: Micro Causs 28mm f/2 - Aperture: f/2 - Focal Length: 28mm - Features: Made by MS-OPTICS - Included: Lens cap Thank you for looking. Size: M-mount