Although this exercise machine looks very unhappy when exercising, it seems the essential task to accomplish: The training of the circular muscle. At the very least raises a slight soreness in the muscles, and also playing the trombone works zusehens easier. This can also be related to the fact that I played more lately in order to examine the training results.
Nevertheless: The unit gets down to the crucial muscles noticeable. A star deduction there, because the upper lip is not fully trained at the same, rather the lateral muscles of the mouth. Probably you have to combine different lip trainer. Damage is there (if you do not overdo it) certainly not.