R-044 Square O-Ring (ID: 3 3/4", CS 1/16", OD 3 7/8") (1 Square O-Ring) The o ring is placed into a groove to secure them in place, and then compressed between two surfaces..
R-440 Square O-Ring (ID: 6 3/4", CS 1/4", OD 7 1/4"), 4PK The o ring is placed into a groove to secure them in place, and then compressed between two surfaces..