You really should look to get as much diversity in the sizes of the taps and dies as you can. That way you will be able to pull the right size out of the box when you need it. Wrenches - All tap and die bits need to be mounted in a wrench. Broadly speaking, they are all roughly the same, with a few notable exceptions. The tap wrench from Muzerdo, is the best on the market.
Construction Material - Steel is the base metal used in the construction of these sets - but not all steel is created equally! Look for steel alloy or, even better, Titanium tipped cutting surfaces.The better the metal the tougher the tap and die so they so they can cut into more Metric/SAE - The size of the tap and die is also important. Metric is of course the European measurement system, SAE are based on US sizes (so use inches instead of millimeters). This is important as you may struggle to use a SAE tap and die set on a vehicle with metric measurements. If the car is made in the US, it probably uses SAE measurements. If it is a European carmaker, it's probably the opposite. If can look for a set with dual Metric and SAE compatibility of course then you don't have t Metal Storage Case - More than with many other types of tools, the storage case is an important part of the tap and die set.
Frankly, because these sets can come with multiple parts, you do want a case that is well designed to keep all the little pieces well organized and safely stored. This item is in the category "Home & Garden\Tools & Workshop Equipment\Hand Tools\Taps & Dies". The seller is "avsom-91" and is located in this country: US.This item can be shipped to United States.