The Stiff Rig relies on a rigid hooklink to stand the bait off a fixed distance from the lead. The rigidity of the rig improves the effectiveness of the bolt rig system and provides a more efficient self-hooking mechanism.
ESP Stiff Rig Bristle Filament is a low visibility, clear, filament with exceptional knot strength and abrasion resistance. However, its key property is that once smoothed out and tensioned into a straight length it has an almost 'spring loaded' quality which provides the ultimate stiff rig material.
It is also the perfect material for chod rigs and the hook section on a hinge rig, where the filament can be set into the perfect curve for optimum hooking efficiency.