I really never thought about a product like this to be honest.until one evening when I got off a plane after traveling cross country and just wanted to get home.only to find that my car battery had died while I had left my car in the airport garage. Someone who was parked close to me had one of these and jump started me.and the next day I immediately went and bought one.I've had that one for a couple of years and I have a bigger vehicle with a bigger battery now so I thought it was time for upgrade, so I ordered this one. So far I have not used it to jump my car since that's new but I did use it to jump start my neighbor's car for her and it worked great. I love that you can use it to charge more than just a vehicle - it's got a port for your phone as well as other gadgets.It comes initially charged but you can top it off quickly and put it in your car for when you need it. It doesn't take up a lot of space, and I LOVE that it comes with the jumper cables built in - so much easier than needing room for those too, which was the case with my old unit.I highly recommend having one of these to EVERYONE but this particular unit is EXCELLENT and it's an excellent price. Buy it and put it in the car. I hope you don't ever need it, but the peace of mind you get from having it is a far greater value than the price you pay for this unit.