The Removable Waist Strap is designed as an optional accessory for our Small and Medium Café Bags, our Citizen Canine, as well as our larger travel bags: the Aeronaut, the Tri-Star, and the Western Flyer When attached to any of the above bags, the waist strap will help distribute weight a bit and stabilize the bag to your body. It's not a sophisticated, padded affair - just a simple strap to add stability when cycling, walking or running.