Carlson 20 Gauge Choke Tube Remington 870 1100 Cylinder. Made from 17-4 heat treated stainless steel these chokes are for Remington (Rem Choke) shotguns. -Steel Lead & Hevi-Shot may be used in all constrictions with the exceptions listed below. -No Steel shot larger than #BB or speeds exceeding 1550 fps should be used in choke tubes tighter than full. -No Steel Shot Larger than #4 may be used in our Turkey Choke Tubes These choke tubes are backed by Carlson s Lifetime Warranty and Made in the USA!