Heavy Duty Pull-Up Resistance Bands aka Superbands - Individual or Set – Muscle X Fitness
First Place Superbands (Resistance Bands)
Super Bands – Top Call Tack & Apparel
Super Bands – GoFit.net
Amazon.com: SPRI Superbands - Resistance Band for Assisted Pull-ups, Core Fitness, and Strength Training Resistance Exercises - Versatile Tool for Flexibility, Stamina, and Balance - 0.5", Orange : Everything Else