RGM Caliber 801
The unique 7 tooth winding click of the RGM 801 movement is inspired by the Illinois Watch Company's "Illini" model. The Hamilton grade 400 is the same basic movement. Hamilton bought Illinois Watch Co in 1927.
It was designed by American watchmaker Charles E. DeLong who had many watch related patents. The original Patent drawing number 1283476 from Nov 1918, Watch Main Spring Click Illinois Watch Co.