Richardson Jumpstarters are the safest jumpstarters on the market. It will not deliver power to the vehicle from our jumpstarter unless it is connected with the proper polarity (if hooked up inproperly, you will get a beep and red flashing light). We make them for all sizes, we can start anything from a garden tractor to a M1 Tank. We make everything from a hand-carry unit to a roll-around cart. We have all voltage, 18-30 for 24-volt systems; we have an 18-volt for 12-volt semis. Our jumpstarters will not fry a ECM-computer.