I wouldn't trust it. There are basically two proven ways to improve stuttering (and they don't work for a lot of people). These are: ​ 1. Certain medications that people don't use much because of the side effects. They also don't work for everyone. 2. Therapy of some kind (can be self taught too). This includes methods like diaphragm breathing, gentle onsets, reading out loud, etc. Sometimes this is coupled with emotional support to boost confidence. Works for a few people, but not much. Some have reported great results, but for most people it only improves it if it even helps at all. The issue with this is that it's somewhat of a hassle to use in the real world outside of a controlled environment. Anything else is probably not real. There is also some evidence for delayed feedback devices that you put in your ear, but from what I understand it's sometimes temporary and it's difficult to use in a real word setting for obvious reasons.