The Industar 61 L/Z  50mm / f:2,8 a great macro lens made by during the Soviet era. It was available in the M42 lens mount.

It is a copy of the Carl Zeiss Tessar 50mm f2.8.

Due to its excellent sharpness and design, the lens is excellent for macro photography using macro rings, which earned it the reputation of not just an excellent staff member, but also a macro lens.

The photo is of the actual item for sale!