All USGI aluminum magazines are NOT created equally. Duramag Speed mags are a true improvement to the USGI style magazine. The magazine bodies are constructed of 6061-T6 aluminum, type-3 hard coat anodized and then finished with a T-360 coating, inside and out. This battle-proven mag is lightweight, durable and feeds every time. Duramag magazines have been the choice magazine for OEM, Law Enforcement and Military Units throughout the world. Features: LipLock technology keeps rounds secured and in proper alignment Lightweight and durable Advanced Geometry Follower remains level for consistent feeding T-360 total coating covers the entire magazine, inside and out EverFlex anti-fatigue spring technology for long life and reliability