The undertaker choke tubes are designed and manufactured for top quality performance while shooting today's lead-based turkey loads. This product has been HS Pro staff tested for optimum inside diameters, producing super full choke patterns, placing 90% of the shot in a 30 inch circle at 40 yards. Knurled end for easy hand installation and removal (no wrench needed). for Remington and Charles Daly 12-gauge shotguns only.