Size 20 KAM snaps are the most commonly used size. However, the "size 20" only refers to the diameter of the cap, which is 12.4mm or about 1/2". The length of the cap prong can vary:
Many people start with standard #20, which is a good size to start with but, as should be expected, doesn't work with all different thicknesses of fabric. Sometimes you need something longer for those thick prefolds, or something shorter for those thin layers of PUL or knit cotton.
A simple way to shorten your caps is to just cut the tips off. But if you're working with a large number of snaps, this could be a time-consuming process. For those who need shorter prong caps, we now have them in a dozen of our most popular colors at KAMsnaps.com.
Here's another tip: You can also use size 16 standard caps instead of size 20 short caps, since they are almost the same length. The #16 will have a smaller cap diameter. However, they can still be used together with #20 sockets & studs.