The Bohning F-Nock with Standard Throat (12-Pack), 0.120/6gm, Kiwi The "F" nock is a small, press fit nock designed for shooters that shoot with a "D" loop on the string Made of durable impact resistant polycarbonate Available in 2 sizes: a double lock standard throat .120 and smooth small throat .106 The small throat fits .088 diameter size string