Pull Up Assist Band, Stretch Resistance Band - Mobility Band - Powerlifting Bands - Extra Durable Chin up Band - 41 inch Straps Each band is 41" long; Loop Band Resistance Levels: Red Color Band - 10 to 35 Pounds of Resistance,(1/2 " *4.5mm); Black Color Band - 25 to 65 Pounds of Resistance, (3/4 " *4.5mm) MAKE FAST PROGRESS WITH YOUR PULL UP PROGRESSION - Don't have strict or kipping pull-ups yet, use one (or better yet two) of these to jump start your assisted pull up training. Used in CrossFit gyms around the world and also works great on a home door pullup bar COMBINE TWO DIFFERENT BANDS TO BOOST YOUR STRENGTH FAST - We recommend that athletes use one thin band and one thicker band together. Start your workout with the thin band. Then when you tire out switch to the thicker band. Then finally to squeeze out the last few reps, add them both together MULTIFUNCTION: - 1. Resistance bands for pull ups 2. Shoulder stretching with resistance bands 3. Resistance bands for front rack stretch 4. Hip flexor stretch with resistance band 5. Leg stretches with resistance bands. And for more ressistance bands training video please search on the web. 100% LIFETIME GUARANTEE - we pride ourselves on superior customer support. If you have any problems, we're here to help!