The Black Rain Ordnance 30 round magazine is a sturdy, reliable 5.56x45 NATO (.224 Remington) AR15/M4/M16 magazine made of advanced polymer material. It is a light, durable and excellent alternative to the standard M4/M16 USGI aluminum magazine. Features: Anti-tilk super follower Sturdy impact resistance polymer with textured grip Heavy duty, non-memory, non-corrosive stainless steel spring Made in the USA - produced by Amend2 Magazines