These extensions are great for the times I have to remove/install a fastener in a difficult to reach area and don't want my sockets/extensions falling apart. I've only used these a few times now, but they seem to do the trick. Note that they will only lock if the female receptacle of the socket or extension you are connecting to has the little indents inside which allow the locking ball to extend outwards—I found out that not all sockets or extensions have these indents.