Plug Style Taps
Tip: There are three basic styles of taps the average guy needs to be concerned about. There is a taper style with strong taper at the business end. This is for through holes adn the taper allows you to get 5 to 9 threads into the hole before tapping begins. Then there is the plug style that can be used for through holes or deep holes that don't need a thread all the way to the bottom of the hole. A plug style is a good all around tap that allows you to get 3 to 5 threads into the hole before cutting begins and also cuts deeper than the taper style. That leaves the bottom style tap that is for threading blind holes as close to the bottom as possible.
High carbon taps are perfect for hand tapping. These taps are are made of tough carbon steel and have just a little give and flex for tapping those tough materials and not snapping them off so easily.
Note: The picture show different size plug taps for clarity only. You are buying one tap at at a time.