Set of 3 HSS Ground taps For general use on non abrasive materials up to 900 N/mm2 unalloyed and low alloyed steel, for through and blind holes, for thread cutting by hand or machine. 1 x Plug Tap 1 x Second Tap 1 x Taper Tap HSS Ground Taper Tap A taper tap has quite a lot of taper to help it ease into cutting threads gradually. Typically, the first 8 to 10 threads are tapered.  Second Tap Second taps are in between plug and taper taps because they have 3-5 threads tapered, which is more than a plug tap and less than a taper tap. Plug Tap A plug tap has almost no taper at the end because it is designed to thread all the way to the bottom of its reach.  Only 1 to 1.5 threads will be tapered.   Plug taps are useful for threading blind holes. Its desirable to thread most of the hole with a taper or second tap first, and then finish the bottom of the hole with a plug tap.