All 18 1/2" barrels are non vent ribbed and have a ramped front sight with a matte finish. Each barrel comes with a Carlson choke tube,manufactured from 17-4 stainless steel except for the rifled choke tube models which are made from 304 high stress stainless steel, installed. All of our Remington 870® replacement barrels are threaded for the standard Rem Choke system. Enhance the versatility and performance of your shotgun with a Carlson's replacement shotgun barrel.? Fits Remington 870 12ga only.