Optima Plus Cal 12 Ga 18.60 Black Ported Choke Tube Extended 5-Set Compatible/Replacement by BillmanArsenal for Skeet, Trap and Hunting.

Specifications:

CONSTRICTION RANGE: This is a 5 pc choke set. Constriction Range: .723 .715 .705 .695 .685. Constriction numbers are nominal. Usually chokes come +.002" /-.002" large/smaller than listed and expands the first 25 shots towards the given constriction.
NO STEEL SHOOTS LARGER THAN: #4 or speeds exceeding 1500 fps should be used in choke tubes tighter than .715 (in this set. 705 .695 .685.). Do not use solid slugs.
OPTIMA PLUS THREADS ONLY: In the Disclaimer section you find more info about what shotguns that MAY HAVE OPTIMA PLUS threads. In the case of Beretta model year is also a factor as old shotgun in new productions runs have new choke systems. Make sure to contact the maker of the shotgun along with the serial number and make sure you have chosen the correct choke system..
MARKING: Each choke has the constriction lasered on the head and body for easy reference. No need to unscrew the chokes.
SAFETY: All chokes are inspected several times. However, we still recommend that all chokes are inspected and cleaned before use/Installation. Such as sticky glue residue (from label and packing), metal shavings or any other dirt or object you do not like to have on your chokes. Just a damp cloth, no tools.