Kratos - 3.5m Length Helixon Retractable Wire Rope Fall Arrest Block - Vertical Use 3.5m - Vertical Only3. 5m Length Helixon Retractable 4. 5mm Wire Rope Fall Arrest Block with Polymer Casing Vertical Use Only Length 3. 5m (286 1520 21). 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