I've had one for years, it is a brilliant device, it is a car starter, for starting dead batteried cars, a power inverter, which means you can run low power appliances up to 700watt consumption, as it converts dc to ac, it has a dc power point for changing items like mobile phones etc, and a built in compressor to blow up your tyres, and it is all packaged in a neat bright yellow hard plastic case with a handle for easy moving, ans well worth the £40 I paid for it, I use it for starting my 7.5 tonne horsebox lorry as it is stood for a while inbetween horseshows, so it is extra heavy duty if it can start a lorry engine.
All this sounds great, but the last time I started the lorry with it, I left it too close to the lorry and backed over it with the front wheel and it was flattened somewhat, well, squashed flat morelike

, but I'm sure you could run over it with a car and it would be ok.