Trace Element Certified Marker, Black, Fine Point Tip, 12 Count ORS NASCO and there are no films and there are no films or laminates to abrade or wear away Tyvek® fabric's durability advantage over microporous film and SMS fabrics delivers consistently better barrier Tight tolerances for snug fit on fastener Used wherever powered drive tools are used to install or remove fasteners Designed to withstand the high torque and force associated with impact tools in repetitive application Features two through holes and a groove to accept a Proto Retaining Ring or pin and O ring to help secure the socket to the drive tool anvil Position at appropriate angle to turn fasteners where obstructions prevent a straight application electronic aeronautic and ship building industries Each marker is identified with the batch number of the ink Writes on most surfaces