New, high quality corner cube (trihedral) prism made by Pyramid Optical Corp. in the USA.

Also called a retroreflector, this prism will reflect light back to its origin regardless of the orientation of the prism face.
Commonly used in surveying equipment and as a cooperative target for laser rangefinders.

Dimensions are 2.6″ diameter x 1.6″ deep with a blacked backside.