Leash thickness, or cuff width, is all about strength and drag. A standard 7mm cuff is perfect for everyday conditions up to head-high. When you’re eyeing heavier, more powerful surf, step up to a 8mm or even 9mm “big wave” leash for extra durability. Thicker means it can handle more pull, but creates slightly more drag. For small, weak waves, a thinner, lighter leash minimizes drag. Match the thickness to the power you’re expecting.