The real question is "for how long can it run your laptop?"
The battery has a capacity of 12 amp-hours, but the documentation doesn't say how many cells this thing has. If it only has one cell, that's about 44 watt-hours. You will have to do the math to see how long that would run your laptop.
Multiply the number of cells by the amp-hour capacity of the pack, then multiply that by 3.7. (Amp-hours are usually specified in milliamp-hours. divide by 1000 to turn mAh into Ah)
So a 6-cell 2200mAh pack would be 6c 2.2aH 3.7v = 48.84 watt-hours. So before accounting for inverter and charging losses, this pack might recharge a fat netbook battery to 90% capacity. The real figure is probably more like 75-80%.