Detent balls

Help! I don't understand detent balls in liner locks, i looked at the liner lock tutorial and i still don't understand. where are they placed?
Michael Abel

The best way to answer your question about where to place the detent ball is to refer to Bob Terzuola's book "The tactical Folding Knife". The reason for the detent is to hold the blade is the closed position, the ball drops into a recess that is drilled in the blade.