Factory Browning Standard Invector .410 Bore Improved Cylinder Choke Tube Produces excellent patterns with excellent uniform densities. All Browning tubes are set to industry constriction standards. Constructed of highly polished, 17-4 stainless steel for the ultimate in performance and durability Specs:br - Material: 17-4 Stainless Steelbr - Pockets: Stainlessbr - Choke Gauge: .410br - Choke Pattern Percentage: 25% - 55%br - Choke Notches: 4br - Weight: 4.8 Ouncesp This is a manufacturer's picture, so the item may not be exactly as it appears in the picture.