Manufactured from 1704 stainless steel for durability and performance; 25% longer parallel section for tighter, denser, and more consistent patterns; Knurled end for easy removal and installation; Laser-marked constriction and size for quick reference; Compatible with steel shot, but avoid using steel shot larger than BB or faster than 1550 FPS in Full (Long Range) constriction; Not suitable for slugs or sabots in chokes tighter than Improved Cylinder; Mid Range (25-40 yards) and Long Range (40+ yards) options available; Backed by Carlson's lifetime warranty for peace of mind