HOW RESISTANCE BANDS WORK:In order for a muscle to grow,its tissue must be broken down through some form of resistance .By constantly breaking down muscle tissue,then allowing it to regenerate,it will begin to grow in size and defintion.The whole concept of the resistance band is performing exercises that use its elastic nature to work specific parts of the body.Traditional weights only provide a steady stream of tension throughout the entire movement.This is sometimes referred to as negative resistance.The biggest benefit of a resistance band is this ability to work more than one muscle at a time creating an efficient,streamlined workout.Another great benefit is the bandsportable and lightweight,so you can work out just about anywhere.KIT INCLUDE:1 Blue Resistance Band (Extra Light) - 10lbs / 4.5kg1 Yellow Resistance Band (Light) - 15lbs / 6.8kg1 Red Resistance Band (Medium) - 20lbs / 9.1kg1 Green Resistance Band (Heavy) - 30lbs / 13.6kg1 Black Resistance Band (Extra Heavy) - 40lbs / 18.1kg2 detachable foam handles2 ankle cuff straps1 door jam anchor1 bag