These choke tubes are factory OEM replacements for 12 gauge shotguns with the Mobilchoke system. These choke tubes will only fit 12 gauge shotguns with the Mobilchoke system.When using Steel Shot - you only use choke tubes marked with the SP (Steel Proof) identification on the side and that you use the most open choke system possible i.e. Cylinder / Improved Cylinder / or Modified. We DO NOT recommend use of Steel Shot in the X-Tra Full Turkey / Full / or Improved Modified choke tube. As with any shotgun, always be sure to check your choke tubes during use to verify that they are tight in the barrel. Loose choke tubes can cause barrel damage.Click Here to see our Choke Tube Collection.WARNING: Use of the Optima HP choke tube in an Optima firearm (without the HP designation) can cause severe damage to the choke tube and barrel when the shotgun is fired. Only use Optima HP choke tubes in these Optima HP shotguns: SV10 Perennia, SV10 Prevail, A400 Family of shotguns, 690, 692, DT-11 and UGB25 Sporting.
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