TIME-SERT5/16-18x.450 Insert Qty 10 p/n 05611

What is the od of the 5/16x18? The whole I’m trying to put this in is roughly .45

Need to know the OD of the 5-16/18 insert or or the major diameter of the tap to determine if there is enough material remaining after tapping.

Are the inserts open end or closed? Also, the tap size shows a 5/16-18 course thread. Should'nt it be larger if drilling out for a new hole?