As per Charles Stratton book, "Pattern 1914 and U.S. Model of 1917", page 53, the "first variation" follower was used by Winchester, and is marked on the underside with a "W". The "second variation" was used by Eddystone and Remington. The second variation will be marked on the underside with an "E", "R" or unmarked. The two variations have different profiles and cross sections.