The Promag® Colt® M4 .22LR 10-Round Magazine is a California-compliant magazine, designed to deliver reliable feeding performance with your Colt-style M4 rifle. The DuPont® Zytel™ polymer body delivers exceptional durability and corrosion resistance. A heat-treated chrome silicon wire internal spring eliminates binding, ensuring the injection-molded polymer follower operates flawlessly for reliable feeding. Not compatible with Ciener and G.I style .22 conversion rifles. Made in USA.