This is the cool first generation Nikon 20mm. It has been updated to AI functionality with factory parts so it will work on all cameras that use Nikon manual lenses (including some digital).
The lens is moderately worn and works perfectly. There is a slight crazing happening to the coating on an inner element. It is light and looks slightly like cracking ceramic glaze but much less severe. I can only see it with a flashlight, it won't affect your image quality. I don't see it when sighting through the lens, even in harsh conditions (see photos). Otherwise the glass is clean and scratch-free. The focus is smooth. There is a small amount of play in the body, but it does not affect focusing or any other function of the lens.