Sizes #4 - 1/2" High Speed Steel Taps And Round Dies Sizes: #4-40, #6-32, #8-32, #10-24, #10-32, #12-24, 1/4"-20, 1/4"-28, 5/16"-18, 5/16"-24, 3/8"-16, 3/8"-24, 7/16"-14, 7/16"-20, 1/2"-13, 1/2"-20 For New Threads Or Re-Thread Damaged And/Or Jammed Threads. Plug Taps Are Used For Thru Holes