The Kiloflex Rings are manufactured using durable plastic and a unique design with a rubber grip coating partially covering the ring to decrease tears on the hands. Sturdy nylon with a heavy duty buckle was used to produce the straps. A unique feature of the Kiloflex Rings is the numbering found on the straps taking the guess work out of ensuring both rings are positioned at the same height. The gymnastic rings are the perfect accessory for ring dips, chin ups and muscle ups.