DURAFIT : Sheath Resistance Band Reinforced Nylon Protective Sheath reduces friction on skin while in use and enhances durability. Uni-Piece Joint provides extra durability and prevents Joint snapping under pressure. Comfort Grip Foam Handle prevents slippage and hand fatigue from continuous intense workout. Complimentary Exercise / Workout Chart provides workout positions and techniques. Commercial Grade material / build quality backed up by a LIFETIME WARRANTY!