Kratos - 20m Length Helixon Retractable Wire Rope Fall Arrest Block - Vertical Use 20m20m Length Helixon Retractable 4. 5mm Dia Wire Rope Fall Arrest Block with Polymer Casing Vertical Use Only Length 20m (286 1520 29). High impact resistant polymer casing. x2 Swivel rotations. Smaller and lighter design. This Kratos Helixon Fall Arrest Block is approved for Vertical use only. For models approved for Vertical and Horizontal Use see the Helixon S models. Complete with swivel snap hook with load indicator at attachment end and karabiner