It's probably a Nikon Ai-s NIKKOR 50mm f1.8, but I'm not very familiar with Nikon lenses, so I apologize if I'm mistaken. It's a pancake lens. This is a junk item. The lens has extensive mold growth on the edges. There is some dust and debris inside. The helicoid feels a little loose. The aperture blades seem to be working normally. Due to the above reasons, this is a junk item and will be sold as-is, no returns or refunds. If you would like more detailed photos or have any questions, please leave a comment. Nikkor 50mm f/1.8 lens, F-mount, fast aperture. - Model Name: Nikkor 50mm f/1.8 - Focal Length: 50mm - Maximum Aperture: f/1.8 - Mount Type: F-mount - Serial Number: 2230206 Thank you for looking.