Each set of Sherwood taps contain one taper, second and plug lead tap:

Sherwood HSS Taper Taps are used to start cutting the thread. They are tapered back from the end 6 to 10 threads before a fully threaded diameter is reached. This allows the tap to be positioned easily and correctly before it starts to cut the thread.

The Second Tap is used after the taper tap has cut threads into the hole as far as possible. It tapers back 3 or 4 threads before full thread diameter is reached.

The Plug Tap cuts threads to the bottom of a blind hole. It is only necessary to use the full set of taps when a blind hole is to be tapped.