This is the EQUATOR™ machine Fixturing plate (M8) replacement part #PCR-13300300-15-8.

This Equator precision ground aluminum base plate can be loaded on and off the Equator gauging system in seconds thanks to its integral kinematic mounting pins. It has a Nituff® hard anodised coating to resist wear and scratching. The M8 threaded holes are spaced at 15 mm intervals to increase the flexibility of your fixture.