Sea-Doo DESS wrist/vest lanyard.Marine grade webbing, neoprene and velcro materials. What is the purpose of the safety lanyard on a PWC? It goes from your wrist or PDF to the unit's cut off switch. In the United States, it is against the law to disable the kill switch on any PWC. You are required to have the lanyard attached to your person at all times during operation. If you should happen to fall of the PWC, the engine will shut-off when the lanyard disengages from the kill switch which makes its recovery much easier. Safety is the main issues here. Many accidents can and have happened due to riders not wearing the safety lanyard.