Monocoque tubular construction for increased stiffness and strength. Permanent co-laminated extension length markings. Outhaul block rigs to a grommet or double sail pulley with no line crossover for friction free out-hauling. Three pulleys for modern in-flight outhaul systems. Foam filled tubing keeps water out whilst keeping weight to a minimum. 50cm in lebgth with 2cm increments. Standard with Triple Clamp Wave, Big Wave, and Pro 1 Carbon 135cm, 150cm.