For use in Mossberg 835 and 935 12-gauge shotguns only. The Undertaker High Density Choke Tubes are designed and manufactured for top quality performance while shooting Hevi-Shot loads (bismuth and tungsten matrix.) This product has been field tested for optimum diameter producing super full choke patterns (puts 90% of the shot, in a 30 circle at 40 yards.) The Undertaker High Density is manufactured in 41L42 chrome-moly, aircraft quality alloy and heat treated to handle these tough loads. It has a blued finish and is knurled for easy hand installation. Fits all 2-3/4, 3 and 3-1/2 guns. HEVI-SHOT is a trademark of ENVIRON METAL INC. and no endorsement, affiliation, sponsorship or other relationship should be implied.