The Oceanus kitesurfing Reel Leash has a lightweight plastic housing which contains a stainless steel spring and spool of webbing with a brass snap hook. Safer than traditional tubular leashes, because when separated from the board, the board will safely fall away from the kiter, once the rider has stoped draging, the spring will reel the webbing back in ,at a slow rate, and in a short time, you will be ready to ride off again, If the board stops violently ( maybe the board digs in the sand or you take a massive wipe out the webbing will snap or the claspwill, both are cheap weak links to replace if this happens, but better than breaking the corner off your board, or tearing your harness, or as a worse case damaging your back.
Watch the video about all 3 real leashes: