i think this product is a very affordable and easy to use item, and the batteries are ones you can recognise and change. Im actually using it at the moment for my neck. its got a good level of vibration to relax muscles. easy to grip, not to heavy. And set up. you just take the plastic bit out stopping the batteries from working, put them back in and press the button and off it goes. with lights on. ive got the blue and white one. which looks rather nice. It comes with AAA batteries, which have fabric hanging off so you cant lose the lid. which is good. There are no replaceable parts, except for the batteries. For the price i think its very good. And my neck is much better.