Specifically designed for clay targets, these extend beyond the barrel for easy removal and installation without a wrench. Minimum gap geometry plus high-resolution "RMS" finish reduce buildup of plastics in the shotgun bore. Stainless steel and black oxide finish. - When used in Browning barrels, barrels must be threaded for Invector-Plus - Browning Midas Grade choke tubes produce tighter patterns than Browning Invector-Plus choke tubes Manufactures Website Address www.browning.com Warranty Information Two year warranty from date of purchase.