As I have only an 8’ x 5’ box trailer to move, I opted for a 350W trailer dolly instead of the more powerful 500W versions offered elsewhere. In spite of adverse reviews, the product arrived promptly and was in good condition. It was easily assembled and mounted to the “A” frame. I bought a 12v battery from Amazon, which powers it well. NB: The product information advises against using this device on grass, which I took into account, even though my driveway is grassed and has a sandy base. Once connected and powered up, the driving wheel kept turning, even when the trailer wheels found several pot-holes in the grass. My partner was asked to stand on the “A” frame, which provided better traction, even though progress was slow. However, on bitumen or concrete, this device is a little ripper, as advertised, and works extremely well. I agree with the caution that this device is not suited to use on grass.