Classy keychain holds your 1.75" Challenge Coin. Easy to use, just unscrew, pull ring apart and slip coin in place, then replace screw! For extra security, place a dab of glue on the threads to keep them tight - otherwise, nervous fumbling with your keychain might cause it to come loose. Measure once.. Measure Twice! This ONLY FITS 1.75" Coins. Not all challenge coins are alike! Please measure your coin to make sure it will fit our keychain. Too big or too small and it will not fit! This ONLY FITS 1.75" Coins. Not all Challenge Coins are the same size. There is no standard size. Please PLEASE MEASURE. You cannot adjust to fit larger or smaller, the diameter of the coin must be 1.75" or 44mm.