No computerized safety features make this the ultimate booster pack.Started a completely flat battery in a car that sat for more than a yearHad a vehicle whose lights were left on all night in -10 degree weather. It was a large engine filled with 20W50 oil. So cold outside the car didn’t want to turn over and definitely wasn’t about to start. This booster pack sat connected to the battery for about 15-20 minutes and it started. Incredible!Connected to the main (trunk) battery under the spare tire in a BMW X5 when the alternator failed. Between the inadequate to start+barely sufficient to keep the car running main 12 volt battery plus this JNC Air clipped to the main battery in parallel, we were able to drive the vehicle for more than an hour with zero further issues until we got the vehicle to the shop, avoiding the need for a tow. It was stressful as we watched the dash voltmeter drop (instrument cluster hidden features that can be unlocked), but we made it. At the time, this particular JNC unit was seven years old, definitely not well maintained (there were a couple of years when we didn’t use it and completely forgot to charge it, while it sat on the floor in a basement) yet it always worked flawlessly and exceeded all expectations.Couple months later a similar scenario with a friend’s V8 Lexus LX. Alternator failed, main battery was completed depleted and couldn’t start the vehicle. Clipped the JNC Air to the main battery under the hood, started the car, left the JNC unit in there and jammed it in place by lowering the hood on the JNC unit; drove to the repair shop (only a few miles away this time) without anything more than the coiled air hose becoming kinked from the weight of the hood.We have helped many neighbors and strangers with this jump starter. This has started numerous vehicles without charging for months. It’s simply that good.This unit has saved us an incredible amount of time, made us countless friends, inflated numerous tires, and tested various electronics (using it as a 12 volt power supply). We felt we were pushing our luck with the JNC, being eight years old and quite abused, so we bought a new one of these and passed this to our tow company friend, who, after another two years, continues to use it on his AAA calls.Bonus: Recharges with a standard extension cord (120 VAC outlet). No need to use external transformers or keep track of special chargers.Other considerations worth mentioning:-This is a professional grade unit - it is large and heavy. Not something most will want to drive around with in their trunks at all times.-The air compressor works wonderfully however the attached/supplied hose and chuck aren’t the best.-The replacement certificate requires one to pay to mail the old unit in plus pay a $150 fee and you get a repaired or refurbished unit back. In other words, the certificate is financially pointless. Better to purchase a new replacement unit with all new parts within.