This replacement or spare magazine is compatible with your Colt M4. It is constructed of DuPont Zytel polymer with injection molded mag follower and mag spring formed from chrome silicone wire. Made in the USA. NOTE: This mag will not work with Ciener and G.I style 22 conversion rifles.
Specifications:

Caliber	22 LR
Capacity	10
Finish	Black
Model	Colt M4
Material	Polymer
Type	Detachable
Model Fit	M4
Brand Fit	Colt
Max Capacity	10