Nope not useless but you should get a 3mhz.

I would think batt would run out and it may not work very long but only based on price. Also the power won't go that high, no doubt.

Also you will pay 20% vat plus a 9% import tax. Plus shipping cost. Even then it might not be what you expect. You could end up having to send it back at a further cost.

There also be charging issues with using a diffrent electrical system in America which might mean spending & £10-20 on a transformer.

A false economy I just experienced buying LEDs from China.

There is also a peice of equpiment call a flex bar by Thera band that could help with exercises.

Good luck