When things aren't happening and you can't quite figure out what to do, go to the dropper. This foam stonefly is designed with a mono loop at the back to attach a dropper. Big and buoyant, this stonefly is the perfect foam towboat for a nymph. Double your chances of catching a fish with a dropper rig. This stonefly is designed to make it easy. In natural. Stonefly fly available in sizes: 6, 8, 10.