Choke tube design takes a big leap forward with Browning's new Invector-DS (double seal) system. The choke's thin wall construction reduces the flare at the muzzle end of the barrel for a sleeker appearance. Browning added a brass alloy band at the base of the tube to seal out gas and grit that likes to migrate between the barrel and tube.
One of the best features of the choke tubes is the ease by which they can be changed. You won't have to experience the ordeal it can be with other tubes, when dirt clogs up the threads and wrestling out the tube can be a wrenching experience.
The flush mount Invector-DS is 3 ¼ inches long, while the Extended Invector-DS comes in at a full 4 inches. The suggested retail is $39.99 for the Invectro-DS and $59.99 for the Extended.