YMW 5/16-18 Roll Form Tap 2-2-1/2 Lead Manufacture YMW Mfg Part Number 388478 Size ( US ) Thread Limit H5 Number of Lobe Grooves 1 Chamfered Bottom Lead 2 to 2-1/2 Finish/Coating Nitride Material Vanadium High Speed Steel Oversize (Yes/No) No Length of Thread .866 Overall Length (Inch) 3.543 Thread Standard.