As a couple have already mentioned I'm one of those that stay away from Harbor Freight like the plague. Any time I go in that place it reminds me of the $2 "Rolex" I bought off of a street vendor in China (But on the plus side at least the watch still works).
Sadly one of the things I've noticed about jump boxes is they are big about advertising cranking amps and small about advertising total energy stored (Amp-Hours). In other words they tell you it has the power to turn over your engine but not for how long. Most hover around 18 Amp-Hr or less if you're able to find a number. One way to research total storage is to find out if the battery is replaceable and then shop for the replacement to get specs.
Here is one that appears to stand above the rest (which also bumps the price quite a bit).
http://www.amazon.com/Jump-N-Carry-JNC950-2000-Peak-Starter/dp/B000KPSA0W/?tag=ihco-20
A couple nice features ....
Nice long #2 GA cables (i.e. HD and can carry a lot of current)
over 900 cranking amps.
34-Ahr of stored energy.
replaceable batt.
50% off at
Amazon plus free shipping if you're a prime member. (and who wouldn't be a prime member?)
The negatives
Still expensive at 50% off.
If you do ever replace the battery it cost the same as a new unit. DOH!
no fancy whistles like air compressor, flashlight, GPS, boom box, invertor, and portable microwave.
Best luck,
Rice