"We fixed these on the front of two large kitchen units which we frequently move around. The brakes didn't work! We then changed them and put them on the back of the units. Hey presto! They worked 100%. Only problem is they don't come with instructions so for us it was "trial & error" plus extra time wasted sorting out the problem. Also it's not normal practice to put brakes on the back of a unit because its hard to get to them. Confusing but a good product once you've got it thr right way round."