"TEMPLATE,SETUP,COORDINATING MEASURING MA;USED DURING THE MECHANICAL CALIBRATION OF THE 3 AXIS TABLE INNER GIMBAL TO AID IN THE MOUNTING OF THE 8 SIDED POLYGON;ITEM IS AN ALUM. RING W/AN I.D. OF 5 IN. AND AN O.D. OF 6.5 IN.;THE RING IS APPROX. 1.75 IN. THICK W/2 INCH DEEP X 1.5 IN. W NOTCHES 180 DEGREES FROM 1 ANOTHER;SERD NC2071"