These precision Rifled Choke tubes are manufactured from 304 high stress stainless steel. Each choke tube protrudes .625 to 1.3 inches from the end of the barrel depending upon which type of firearm the choke has been specifically designed for.- Right hand rifle twist, which is a 1 in 35- Groove diameter of .730 of an inch in 12 Gauge- Matte black finishIf you are looking for improved accuracy from a smooth bore barrel, these fine choke tubes will improve your groups. Fits: Remington 12 Gauge(This Product does not fit the Remington Pro Bore or the Remington Spartan Models)