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. Three pulleys for modern in-flight outhaul systems. Foam filled tubing keeps water out. 50cm with 2cm increments. Standard with Triple Clamp Wave, Big Wave, and Pro 1 Carbon 135cm, 150cm.