Seattle Fabrics: https://www.seattlefabrics.com/
Dutchware Gear: https://dutchwaregear.com/
Ripstop by the roll: https://ripstopbytheroll.com/

A Plus Products: ​http://www.aplusproducts.net/wp-content/uploads/2018/01/S18-S19_Flyer_Summer_Web.pdf

• It looks like this is the source of the slide buckles on the Simple Pack