Punching out 510 cold cranking amps, this power pack spun our test car's engine significantly quicker than any other product in the group. But then this is a serious piece of kit, really aimed at professional users and large-engined vehicles. Apart from a solitary cigarette lighter socket, all other features are safety related. A key-operated isolator provides arcing protection and a buzzer prevents wrong connection. Very pricey in this company.