The bead butt like its name sake has a bead in the rear of the hook. What this does for the pattern is give it a walk the dog or jerk style movement. When stripped slowly the fly tracks normally. Where this fly shines is when it's retrieved with quicker stop and go strips causing the fly to move erratically darting side to side. This movement mimics a dying or injured baitfish which predators find irresistible. Ahrex NS172 #2 hook.
