Encounter Assisted Pull-Up Band,Resistance & Stretch Band,Power Band All Bands Circumference=50cm,Width = 5cm. Size 4 - Black -(1.1mm) Thickness - Resistance (100-120lbs) Size 3 - Green -(0.9mm) Thickness - Resistance (50-75lbs) Size 2 - BLUE -(0.7mm) Thickness - Resistance (20lbs) Size 1 - Red -(0.5mm) Thickness - Resistance (10lbs)