The settings of these units seem to confuse some people. They find it hard to adjust the modes and intensity levels to get the perfect massage for themselves. We also saw some complaints about the units not being strong enough or too strong for some of the buyers. This is really an individual issue because not everyone has the same tolerance for this sort of stimulation and massage. A few people stated that there was not much difference in the intensity levels or modes of some of the devices. It will take some time to try out the various levels to see which ones work best for you.