This mirror is mounted within a mount for 20mm and 25mm mirror sizes. The mirror has high reflectivity and is gold plated for this reason.

This is the holder of 20mm and 25mm mirrors. The mirror mount has a seat for the mirror behind the large cylindrical part at the front. There are two screws in the back for minor adjustment of the angle of the mirror. There are M6 threaded holes on two sides of the mount for attaching to a machine or other device.

A 20mm lens and final mirror needs to be mounted in this part. The lens mounts in the tapered (conical) section of this part. Notice the component showing partly blue. This is the air assist tube inlet fitting.