A short zipper
The micro sling’s zipper is too short. I have an IPhone and it is quite difficult to put it into the compartment because of the length of the zipper. The zipper should be a little longer to accommodate the length of a cellphone with its case. Perhaps that blue safety “lock” for the zipper should be removed. It is too cumbersome to use anyway. You should rethink the locking concept for the zipper.