The business end of the 8:1 main downhaul. A simple loop of spectra line with a plastic ball on one end and a bowline on the other is passed through one of the beckets. Once the main is hoisted, the bowline is passed through the tack kringle ("grommet"), through the shackle on the other block's becket, back through the kringle and looped over the ball. Makes for a very secure and easy to release arrangement.