Your time is too valuable to spend it looking for lost detent balls when they take off - and rest assured, they will!!! And, when you can't find them, if the time lost looking isn't bad enough, the factory often gets as much as $1.50 EACH for replacements. So - you need this Kit! Detent balls are everywhere there's a "click" adjustment in a gun or a jig; they're even used as check balls in some semi-auto gas systems. Kit contains 20 each of the 8 most common sizes of detent balls found in firearms, and is packed in a special "pill-box"/bench tray case. Includes detailed cross-reference table of all the gun parts list detent balls we could find. (Special thanks to our tech staff and Gary Thiry, Sacramento, California, for working this one out!)