The product is an early Nikon BR-1 (Type 1A) Bellows Reverse Macro Ring Adapter, designed for Nikon F lenses with a 52mm front lens. This lens adapter allows for reverse macro photography by twisting on to the lens and coupling with the Nikon F fitting. Made in Japan, this Nikon branded adapter is a high-quality accessory perfect for photographers looking to explore macro photography with their Nikon F lens.