Parallels (engineering) — Engineering parallels are rectangular blocks of metallic, frequently Software steel, stainless steel or cast iron, which have four or 6 faces floor or lapped to a exact area complete. These are applied when machining using a miller, drill or every other… … Wikipedia David a Fort Myers https://engineeringinspectionssyd05812.like-blogs.com/19866697/air-receiver-tank-no-further-a-mystery