ZELX SS 1/4-28 H3 Spiral Point Plug Tap Manufacture YMW Mfg Part Number 382614 Size (Inch) Thread Limit H3 Number of Flutes 3 Chamfered Plug Lead 3 to 5 Finish/Coating Black Oxide Material Vanadium High Speed Steel Oversize (Yes/No) No Length of Thread .591 Overall Length (Inch) 2-1/2 Thread Standard UNC Tapping Materials: Stainless Steel, Alloy Steels and Ductile Iron Tapping Stainless Steel: 12-70 SFM Tapping Alloy Steels: 10-45 SFM, Tapping Ductile Iron: 15-60 SFM