Avian X Waterfowl 12 Gauge Remington 665 Waterfowl Choke Tube - Dense / even patterns and maximum kinetic energy Unique wide groove technology helps separate pellets from the wad Straight rifling stops wad from spinning and focuses more pellets on target Radical porting keeps gasses away from the shot string Castle cuts on the crown lock choke tight in barrel and provide exhaust channels for gasses to quickly escape Rated for steel, tungsten, bismuth and lead High strength tempered steel for maximum durability High performance black PVD finish for smoother shots and easier cleaning Polished end face for better seating / sealing inside the barrel