Cnc extender adapter made especially for 1/4" Shank router bits., #47640, (D) diameter 3/4, (D) diameter 3/4, overall length (L) 3-7/16, max RPM 18, 000, L1 1-1/4, L2 1-15/32, L3 5/16, D1 1/4, 47640 1/2 inch Shank CNC extension adapter for 1/4 inch Shank router bits