One of the ways that you can extend the life of your bag or sling is to take care of the zippers. Most of us at some time will put more items in the bag than it is designed to carry. When you do that, it’s tempting to use the zipper to bring both halves of the zipper tracks together in order to close the bag. In other words, we pull up on the zipper, trying to use the zipper as a way to compress the items that are in the bag while getting the pack closed. This puts unnecessary strain on the zipper teeth, the zipper slider, and the zipper seam.
A better method is to pull the opposing zipper tracks together with two hands, then with one hand holding the zipper tracks close, use the other hand to gently pull up the zipper. This method is much less stressful on the zipper and related zipper parts. Be careful not to overpack!