The Multi-Pack Heavy Resistance Bands include 4 different strength-resistant bands. Made from durable latex, these resistance bands aid in pull-up assistance, add resistance to stretches and bodyweight exercises, and add resistance to the barbell for a variety of lifts. Each set of resistance bands measures 41-inches in length and features the Titan Fitness logo. The Purple bands (25-80 lb. resistance) and the Green bands (50-120 lb. resistance) are made for ultra-resistance for intermediate or light-weight beginners with pull-ups. The Blue bands (60-150 lb. resistance) are for people over 200 LB that are beginners with pull-ups and for weightlifting, and the Orange bands (70-170 lb. resistance) are made for adding weight to powerlifts.