Ring diameter is 15.594 in min and 15.594 in max; twelve holes 0.272/0.775 in deep dia; 120 degree csk 0.340 to 0.310 in dia; has two acess holes 1st holehas 3 holes 0.223/0.217 in dia; width between holes 1.5000 in., holes are 0.275 to 0.295 in deep; attaching plate has two holes 0.192/0.186 in dia