Standard invector tubes are available in chokes ranging from cylinder to extra-full. They produce patterns with excellent uniform densities. All Browning tubes are set to industry constriction standards. Chokes tubes are flush and made of 17-4 stainless steel. Standard Invector choke tubes fit only Browning shotguns designed for Standard Invector and are not for use in shotguns showing Invector-Plus or Invector-DS on the barrel(s).