Thanks to an elongated cone, Optima choke Plus guaranties an excellent shot pattern and are the best in term of performance, resistance and reliability. The new shape improves resistance to the pressure and speed created by 3.5" cartridges with steel shot. The special heat treatment assures a high level of durability. These choke tubes will only fit the 12 Gauge Optima choke Plus shotguns.
Barrels that use the Optima-Choke Plus will typically be marked 12 gauge 3 1/2" with no other identifying code mark in the immediate area of the gauge marking.
Optima-Choke Plus choke tubes will be marked Optima-Choke-Plus.
The start of the threaded portion of the Optima-Choke Plus tube is located a nominal 41.9mm (1.64 inch) from the breech end of the choke tube.
The length of the threaded portion is a nominal 10 mm (..394 inch).
The major diameter of the choke tube thread is 20.58 mm (.810 inch).
At this time the Optima-Choke Plus system is typically used on the Xtrema, Xtrema2 semi-automatic field guns and 471 Silver Hawk side by side shotguns (12 Ga.).