The Crass Model Ithaca Double (1888 to 1901) used V-Springs, an underbolt with a dollshead rib extension, and later just a plain rib extension. The Lewis Model (1901 to 1906) continued the use of a V-mainsprings and a leaf sear spring, but added a bolt through the rib extension. The Minier Model (1906 to 1908) introduced the use of coil mainsprings and added a second bolt on the rib extension --


From September 1907 Field and Stream.

The Flues Model (1908 to 1926) simplified the use of coil mainsprings, and retained the three-bolts of the Minier --


From May 1909 Field and Stream.