This standard, steel formed heatshield is 13.5" and features elongated cooling slots allow maximum, quick dissipation of heat for ultimate protection against burns. It easily adapts to most 12, 16, 20 gauge and .410 pump shotgun barrels. The easy install requires sliding the shield over the barrel and securing with the supplied hardware. This heatshields should not be used on Mossberg Mariner or Remington Marine Coat Shotguns.