Metabones Speed Booster lens adapter.
- Condition: Used but looks in good condition
- Included in the sale: Just the lens and caps

Belonged to my late father so I don’t know anything about it so can answer any technical questions. The info below is from AI

Key Identifiers & Specs
- Optics: Features an internal optical element designed by Caldwell Photographic to reduce full-frame lens image circles down to APS-C / Super 35 sensor sizes.

Functionality:
Increases the maximum aperture by 1 stop (making lenses brighter) and reduces focal length by 0.71x (widening the field of view).

Serial Number: 1011002642

Features: Includes a removable Arca-Swiss compatible tripod foot/mount visible on the right.