Punched out of 3mm black Insertion Rubber
A bolt circle diameter (BCD) or pitch circle diameter (PCD), sometimes simply called bolt circle or pitch circle, is a common term for when a number of screw holes for bolts are evenly distributed with their centers along an imaginary circle with a given diameter.
BCD / PCD		 178mm
Bolt Holes 	 	  4
Outside Flange Diameter	 215mm
Bolt Diameter 	 	  M16