The nylon strap included in the set is very durable, tear-resistant and adjustable. This allows you to easily mount the ball at a suitable height for each boxer. The flexible, rubberised Benji strap brings speed to the ball. The tighter the Benji strap is fastened, the faster the ball returns from your stroke. In addition, the set includes 4 metal S-rings and a sturdy PVC buckle for fastening.