I have one of these. I didn't believe in them till a buddy at work bought one. He bragged and bragged about it, how it's small and worked great. Start a car with a dead battery without any problem. So I went out and go one from Amazon and it does it's job. What's great about it too, is that it has two USB ports and I can charge the cell phone. I never had the need to yet, but it's capable. Under $100 bucks.