A reel that is best suited for trout spey applications should have a "full frame" design to help manage the thin running or shooting lines often preferred by trout spey fisherman. This solves a couple of problems. A full frame prevents the skinny line from being jammed, damaged, or pulling through the gap between the spool and reel with traditional architecture. It also adds weight. Heavier reels balance these longer rods better and help stabilize the rod throughout the casting stroke.