Optima choke tubes are longer and slimmer than conventional Mobilchoke tubes with an elongated cone to minimize pellet deformation to enhance the concentration and distribution of shot patterns. These flush fitting chokes are for 12 gauge shotguns with the Optima-Choke system only. SPECIFICATIONS: Mfg Item Num: JCOCN13 Category: CHOKE TUBES Type :Flush Gauge :12 Gauge Choke Size :Full Configuration :Optima-Choke Finish :Silver Chokes Included :1 Recommended For :40 yds Material :Steel Ported :No