Google brings up a lot of stuff about sewing things for rock climbing and the like, or ad's for sewing machines with them, but nothing I found that tells just what they do & how they work. BTW (& off topic) those rock climbing forum have the same questions you guys do here. Only, think of it, you are hanging in the air 200 feet up and suddenly you realize someone, who knew nothing about sewing, used a $69 plastic sewing machine from Walmart to sew your webbing gear...