This is a telephoto accessory that fits on the front of your 2.8F (and maybe others with size bay III filter mount) Rolleiflex TLR with size bay III and turns it into a 116mm lens.
The lenses are made by Carl Zeiss and I presume best optically with the Zeiss lenses, however, will work also with the Xenotar (not Xenar). These were produced originally for the 75mm f/3.5 TLR however they made adapters for the 80mm f/2.8 versions. Sometimes you can find the adapters to change this to fit other Rolleiflex models.
The condition of this item is overall excellent - the glass is free from scratches or issues. There are some cosmetic-only signs of wear on the metal where it mounts. No shade or leather case is included in this one.
What you want to look for on these is the bottom (taking lens) can get dented and prevent filters to mount. These have a little foot that extends to help the camera from tipping forward when mounted.