Bolex Yvar 1.8/13 AR Macro lens

Objective Paillard-Bolex (Swiss brand).
Paillard was a Swiss company famous for its 8mm and 16mm film cameras and for the interchangeable lenses it produced for its models (particularly the Bolex).
It's a small macro or close-up lens, probably intended for an 8mm or 16mm camera. The notches with values like 0.3 – 0.35 – 0.4 indicate the focusing distance (in meters).
The objective shows focusing values between 0.3 and 0.4 meters (or nearby), typical of Drop-In MACRO close-up lenses, which are inserted in front of a standard lens to reduce the minimum focusing distance.
The phrase 'Paillard Switzerland' confirms the origin: Paillard-Bolex produced this type of accessories both for its 8 mm/16 mm movie cameras and for Leica mounts.