The jumpers he bought for $9 are listed regular price $40.CasperCasper said:I saw these on TV the other day and laughed but they have some promise. I looked into them a bit. 12500 mah (battery capacity) equates to 12.5amp hours. This means that this thing will do 150amps (typical car starter load) for around 5 minutes. The catch to that is the C rating of this battery would need to be about 13 which I would say is way high for a 10 dollar unit (The C rating is how fast this thing can discharge). Add in the resistance of the cables and other systems that will draw from it and I'd say these things are iffy at best. I'd like to know your experience though because perhaps they are high C rated cells.