20Ah for 23 bucks? Seems like it's almost too good to be true. Wouldn't surprise me if it was just half that, would explain the price and weight.
I'll find out if this is true. Hiking buddy of mine pointed it out on Friday, so got one on the way. Was $18 when he called it out, $23 by the time I ordered. Apparently they have a bunch of random stuff like this. They must have some outdoorsy folks in marketing.
Thru hikers just kind of find this stuff. They are obsessed with weight and recommendations spread quickly through word of mouth on the trail and on forums.