5/16-18 Full Thread Hex Tap Bolts 18-8 / 304 Grade Stainless Steel Stainless Steel Fully Threaded Hex Head Tap Bolt Screws Have a Hexagonal Head Used With a Wrench or a Socket. Hex Head Tap Screw Bolts are a Primary Fastener Type For Many Long Thread Applications. These Hex Cap Tap Screws are also known as Fully Threaded Hex Bolts. Made of 18-8 / 304 Grade Stainless Steel Which is an Austenitic Grade of Stainless Steel. Right Hand Thread, UNC Please View Matching Nuts & Washers Below. CONTACT OUR SALES DEPARTMENT FOR BULK AND WHOLESALE PRICING.