Safe And Durable Materialkingroad Resistance bands are made from of natural material,which is strong tear-resistant, stretchy, durable and can withstand extreme tensile force. The greater the pull value, the greater the resistance you will feel. Specification Light Grey(8-15 lbs), Best for speed barbell training and shoulder mobility. Medium Grey(15-35 lbs), Beginning bands for resistance and barbell band training or just a little boost for pull up assist. Grey (25-65 lbs), Medium tension for resistance training and pull up assist. Dark Grey(35-85 lbs), Ideal for pull up assist, High tension for resistance and advanced banded barbell training. Black(50-125 lbs), Ideal for pull up assist. Versatile Workout BandsThese stretchy fitness bands can improve your strength and freedom of movement in all major muscle groups. Perfect for yoga training, stretching, strength training, and flexibility exercises that can have positive effects on health. You can also use them to stretch be