This set includes 4 MoonRun elastic bands (CHOOSE SIZE) :
Light set-suitable for users who weigh less than 90 lbs; less than 40kg.
Medium set-suitable for users who weigh between 90 lbs to 200 lbs; 40kg to 90 Kg.
Heavy set-suitable for users who weigh more than 200 lbs; More than 90 Kg.