Choosing A Surfboard Leash
Getting the right length leash is actually pretty simple, just choose one roughly the same length as your board! So If you're riding a 5'10 fish or 6'2 thruster, go for a 6' leash, or an 8' leash If you ride a 7'10 mini mal etc.
Different Types of Leash
Most regular surf leashes will have an adjustable ankle cuff to attach to your ankle and a 7mm thick polyurethane cord with a swivel at each end to prevent tangling, Comp leashes have a thinner cord, usually 5mm thick so as to create less drag as they trail in the water when surfing, being thinner they're not as strong and so are only really used in smaller surf. Big Wave leashes have a thicker 10mm cord to give them more strength and are used in larger more powerful surf.