My son has had a cello for a while and I have been meaning to buy one of these since the last end stop was lost. Unfortunately I left it to late and rather than just paying the £4 I now have to replace a scratched wooden floor and a gore-tex shoe which was puncture (fortunately it missed his toe!!!).
It really is worth it to stop unfortunate accidents.
Fitting was a breeze and it has not fallen off at all.