I exercise a lot with my Apple watch. As everyone knows, your wrist size changes a lot during the day and the key to having the heart rate monitor work correctly is a firm, non-slipping grip. The sports band is difficult to tighten, especially if you are in the middle of exercising. The Milanese loop or the leather loop is the right idea as they are easy to tighten on the fly, but the materials are wrong. While leather would probably work fairly well, it is too expensive to be used as a sports band and would get stained by sunblock, etc. The metal Milanese loop slips too much. What is needed is a flexible sports band constructed with a magnetic loop closure. Anyone know of anything available like this yet?