It called the double friction method, an innovative hack of the Laser's hiking strap setup.
The idea is to use 7mm main sheet laced through the eyelets at the back of the cockpit to create friction points allowing the hiking strap to be adjusted as needed on the water. A worn piece of main sheet is recommended as it has more friction.
It is a clever adaptation of the existing eyelets, a work around for the original crude design.
In reality its a little too tricksy and most club Laser sailors just thread some cord through the strap and the eyelets and secured with half hitches.
The 21st century way to use a buckle and velcro. This is the Aero hiking strap, adjustable in two places, too easy.
