Allstar 11/32 inch x 0. 62 inch O. D 0. 531 inch Machine Tool Guide O. D Engine Valve Seal (Pack of 16) feature engine valve seals. They are 11/32 inches and . 620 inches o. d. for use with a . 500 inches o. d. machine tool guide. The machining is required for most installations. The seals have spring loaded wipers for maximum oil control and are sold as one set of 16 pieces.