This article explains how to use the concept of "flashing the lane" in defense in ultimate frisbee. Flashing the lane is when a defender moves quickly from the deep space to the cutting lane and then back again, taking away the cutters passing angle and denying them the chance to make a disc-winning throw. The article covers the benefits of the technique, such as denying a cutter the inside lane and the ability to use up the clock. It also outlines the techniques involved, such as reading the offense to anticipate the cutting lane and setting up the defender in the correct position to flash the lane. The article also provides helpful tips, such as staying active and keeping your head on a swivel.