JET 701357 - 12mm Flex Head Ratchet Combination Wrench Plumbing Tools "PSA" type pad which is

"PSA" type pad which is balance weighted to reduce vibration Adjustable speed regulator Equipped for use with a central dust collection system for work place safety Standard accessories: 6-Inch PSA 6 Hole sanding Pad 905317

It is a heel jaw with pin assembly

used for smoothing surfaces and rapidly removing sharp edges and burs on iron and steel flatwork

This product is used for ball-casters

JET 701357 - 12mm Flex Head Ratchet Combination Wrench Plumbing Tools "PSA" type pad which isExclusive torque drive non slip open ends , 72 tooth ratchet mechanism exceeds the ansi torque ratings for a fixed wrench by more than 30 Percent , Superior grade 6140 chrome vanadium steel , Fully polished surface resists corrosion , Sets complete with plastic carrying rack