in 1915 the Jostam AntiFlinch had become available, along with the Jostam 3-Ply. The illustration looks like the former.
The Justam Anti-Flinch recoil pad did become available late 1915 or early 1916, Patent No. 1,156,293 granted Oct. 12, 1915. The multiple ply sponge rubber pad was the Huntley, and Stephen A. Huntley's patent for it, Patent No. 1,222,291, was granted Apr. 10, 1917, and assigned to the Huntley Manufacturing Company of Omaha, Nebraska. It was originally marketed by Huntley. From a circa 1916 H & D Folsom Arms Co. catalog --
After The Great War it was added to the Jostam line.
The pad pictured on the Baker SBT in the catalog cut has five round holes through it side to side. I know I once upon a time found information on that pad, but I can't seem to lay my hands on it now.