Commercial Grade Hinges are .134 thickness, use for 1 3/4" door thickness. Hinges have 2 ball bearings per hinge, Square Corners, 4.5" x 4.5" - Made of Steel with Steel pin, Non-rising removable pin with button tip and plug - For Use with Doors with Normal usage or doors with closers, including UL Fire Rated Door Openings approved for single doors up to 4/0 x 8/0 and double doors up to 8/0 x 8/0. - Furnished standard with All wood screws (1-1/4" x 12 FPHW) and All machine screws (1/2" 12-24 FPHM) - ANSI A8112 The Safety Stud (SH) 3/16” (4.8 mm) projection is a feature that places a stud on one leaf and a locking hole on the other leaf. When the door is closed, the stud is anchored into the opposite leaf. Even if the hinge pin is removed, the door is secure because the leaves are locked together.