The Promag Standard 10rd 22 LR magazine is the perfect fit for your Colt M4 offering reliable performance and durability. Crafted from tough DuPont Zytel polymer this lightweight yet strong magazine features an injection molded follower and a mag spring formed from high-quality chrome silicone wire for smooth operation. Built in the USA it ensures precision manufacturing and dependable function. Please note this magazine is not compatible with Ciener or GI-style 22 conversion rifles. Perfect choice for those seeking a durable dependable magazine designed specifically for Colt M4.