A drawstring bag, or cinch-up backpack, is a small, lightweight bag that is adjustable with two strings. You pull the strings to close the bag, and pull the bag apart at the top when you want to access the items stored inside.
Cinch bags—also known as drawstring bags or gym sacks—are an easy and convenient way to carry gear to and from the gym. Because gym bags are less structured than backpacks, they can more easily accommodate bulky objects like sneakers.
Material. The most popular drawstring backpack material is probably nylon. Nylon is extremely strong and durable, so it's a great choice if you'll be hauling heavy loads with your bag. It's also mildew-resistant and quick-drying, making it a common selection for outdoor use.