I just got this and went jogging with my dog. I brought it to take my iPhone XS Max with me because it doesn't fit into any of my running clothes. I have a protective case for my phone and it barely fits in a zip pocket. Getting in and out was a little awkward. I found it easier to get in and out of the flap pocket and felt really secure even though it wasn't a zip pocket. Another pocket with a flap was good for a dog leash. As for size, I usually grab running shorts in a small size and there I put the belt on and it fits me perfectly. I wear it on my hips, not my real waist. It actually seems to help hold my running tights in place which is an added bonus.