Precision-machined 17-4 stainless steel with a black finish. These chokes have 25% longer parallel sections for more consistent patterns than conventional tubes. Knurled end allows quicker installation and removal. Constriction is lasered on the ends for easy reference. Use with lead, copper-plated, nickel, Hevi-Shot®, bismuth, tungsten and steel shot. 12 ga. only. (Steel shot larger than BBs and faster than 1,550 fps cannot be used in the Full constriction.) Lifetime warranty. Models: Full, Improved Modified, Modified, Light Modified, Improved Cylinder.