Sorry to ask a silly one, but I come more from the world of electronics and not mechanical. I am looking for the name of the mechanism that is commonly used on umbrellas, luggage pull handles, and walking canes to provide an adjustable handle length. It consists of a spring loaded button on an interior tube that engages into a machined hole on the outer tube. My google fu failed me. I am incorporating one into a design I have but I dont know how the spring and button attach to the interior tube. If anyone has a model I would appreciate it.