This is a mount adapter from Lomography, a Czech camera accessories manufacturer, with a new price of 21,000 yen. I purchased this unused on Mercari and used it about twice to mount a Voigtlander Nokton 40mm f/1.4 on a Nikon Zf. It has a helicoid, allowing for close-up shooting with M-mount lenses. The helicoid has a locking mechanism that clicks into place, so it's convenient and prevents the helicoid from moving unintentionally. Ultimately, I've been using AF Z lenses more often, so I'm selling this. The original box is included.