Yosoo 1/2-28UNF HSS Machine Plug Thread Bottom Tap Tapping Slag Threading Drill Bits Tool 12mm x 8mm Increased heat resistance, extending the life of the tap, tap to make more resistant, and can attack the stainless steel parts. High hardness, high wear resistance, for stainless steel, iron and other drilling. Material: HSS Size: 1/2-28UNF Purpose: For processing nuts or other parts common with the internal thread (ie wire tapping)