This is the Knotty Utility Strap: an iPhone strap that lets you carry your smartphone with you around with peace of mind. You can wear it on your shoulder or simply wrap around your hand to handle your phone. It has a rotating carabiner and adjustable design. This particular version features 8mm polyester rope. It is compatible with most cases.
Knotty is available in 6mm and 8mm versions. Various gorgeous colors are available for you to choose from.[where to get it]