This one is 20000mAh, there is a 38800mAh unit under "similar units" for $15.79, albeit without the compass.
I have that one, bought from Amazon. The solar charge,. although it seems to work, is practically worthless ( I mean how much can it produce - 1W tops? - after keeping it under a lamp for a few days it actually lost charge, LOL), and I suspect the battery capacity is also not quite as advertised, as after charging my 5000mAh phone (probably used 3500mAh or less) from a full unit, one light disappeared (so I may have used closer to 25% - meaning the battery may really only actually hold closer to 14000-20000mAh, not 38800mAh... I have not actually measured how much it holds, for that I would probably have to drain it, and figure out what the lights actually indicate - this was just an educated guess after a single charge, repeated a few times with same results). Still, the light is handy, and the unit is sturdy, small, and light, for the price it's probably a good deal.