In summer, people usually wear less clothes. Maybe a lot of clothes don't have pockets to put things in. Especially for women, they need to carry more stuffs at any time. So they usually bring a bag when going out to contain all kinds of things. But if it's outdoor sports or riding a bike, it's not suitable to take a bag. In this case, the belt wallet can be used. It is tied around the waist like a belt, and there is a small zippered pocket in the front that can be used to hold some small things, such as mobile phone, pocket money, sunscreen, etc. Of course, large items cannot be held. But for outdoor sports, it's better to bring less things.