28 Piece Transfer Punch Set. 3/32-1/2" by 64ths and 11/32" Black oxide finish. Heat treated tempered tool steel for longer life. Undersize .0025". Used for transferring of threaded, drilled and tapped holes. 28-pc. CENTER PUNCH Set Steel Transfer Punch Machinist Thread Tool Kit Set.Heat treated, carbon steel construction.Black oxide finished for durability. Select one of the punches, hold punch shaft with one hand while gently tapping a hammer (not included) on the flat top of the punch to make a mark on your selected material that is visible for your center punch, then use your existing center punch (not included) to make a dimple Eliminates guesswork when transfering threaded, drilled or reamed holes in sheet metal. Eliminates the guesswork when transferring punches through holes.A transfer punch set is a punch set in an index with a specific outer diameter that is non-tapered and extends the entire length of the punch, except for the tip. It is used to tightly fit the tolerances of an existing hole and when struck precisely transfers the center of that hole to another surface. 4-7/8" long: 3/32" to 1/2" by 1/64" increments, handy 17/32"punch