(md) New Acme 1/2-13 X .687" Long Stainless Steel Heavy Duty Key Locking Threaded Inserts. Part Number 217-076306, MS51831-106. Internal thread is 1/2-13 and external thread is 11/16-11. 41/64" tap drill size. Listing is for 5 pieces, new from the bulk package shown. Listing price includes FREE SHIPPING!!