A while back I received a phone call from a company that was having problems with some rental tents. The tents used web straps with plastic double bar buckles and the buckles were breaking. Photos shot back and forth and it was evident the tent manufacturer was using the buckles improperly which was causing the problem.
If you check out the buckle on the left (the one without webbing) you see three horizontal “bars”. The top one (with teeth) is part of the locking mechanism for the loose end of the strap. The middle bar is where you should be sewing your webbing like the buckle in the center with the green webbing. The bottom bar is NOT designed to be used as an attachment point. The buckle on the right with the red webbing is improperly assembled and with any sort of load, the bar will break.
We sell double bar buckle straps in widths from 3/4″ to 2″. They come in any length and our minimum order is one (1) strap. For those who want to make their own straps check out all of the buckles and webbing we have in stock.