I've only used it for a week because I was out of town... I am impressed by the quality of construction and customer service. I got it to improve my bone density and for lymphatic drainage. I use it in the morning at higher amplitude and in the evening at low amplitude, low Hz for relaxing my muscles. I have only been able to tolerate the high amplitude at 25 Hz which is not ideal for building bone density, because it is rather teeth-jarring and eye-ball shaking for me at higher levels. I hope I can build up to higher levels. Won't know if it's working for two years until my next DEXA.