The Thule Passive Lock Strap offers a simple solution to secure your bicycle strap rack to your vehicle without the pains of adding another key to your ring or having to remember some obscure number for the rest of your life. Just loop the round puck around the rack and place it in the trunk or hatch of your car and you're set. The nylon strap ensures the two steel cables won't scratch your car, bike, or rack. And, of course, it makes sure you still have your rack every morning you wake up.