G-Jaws are designed to fit your currant vise (4,5,6 or 8") and use our G-NOB gripper buttons. G-NOB Gripper buttons are excellent because of their flexibility and log life. Grip odd size materials, rotate the GNOB button a little if it gets dull for a brand new edge! Add buttons for more gripping power. "GET A GRIP, LET ER RIP!"