The Choke Tube Flat Wrench is designed for use with Standard Invector choke tubes only. Please note that Standard Invector, Invector-Plus and Invector-DS have different choke designs and it is important to select the correct wrench for removing and reinstalling your shotgun’s choke tubes. Many extended tubes are easy to remove with fingers, but most gauged choke tubes have wrench slots hidden inside that only accept the correct wrench for that gauge. All gauges, except .410.