I purchase a set of Sonic Clean between machines, they are just garbage! So, don't buy it at all cost ! I am very disappointed with the machine. Totally fooled by the tv ad! The cost was came out total $35.85 for two machine. If you return it you will only get back $19.95, and you have to pay for the cost for shipping it back! So, I don't know if I return it back or not? I hope no body buys the machine anymore!