Extreme String (40mm) Black gives an amazing appearance of long dyed hackles with embedded metallic glint threads making Extreme String (40mm) Black the ultimate predator hackle. Use for Pike, Muskie, Bull Trout, Saltwater or any predators!. With 40mm hackles Extreme String (40mm) Black produces extreme flies, hence its name. Use as hackles, body wraps, as a palmered chenille for incredible effects and movement. Extreme String (40mm) Black works amazingly well if brushed with a toothbrush to separate the fibers even further. Either brush before or once tied to add even more bulk without weight to this stunning material.