These magazines went through a lot of testing, tweaking, and then more testing to make them perfect. They have lots of great features: True, heat treated, aluminum bodies with a corrosion-resistant finish and an improved MIL-STD follower that presents the cartridge correctly. Available in 20 and 30 round capacity with a choice of either chrome-silicon spring or MIL-STD stainless steel spring. The chrome-silicone spring works better for most competitive shooters because it won't take a set and provides uniform spring tension for the life of the magazine.
AR-15, Issue:10, Page:053
Brownells Christmas , Issue:4X, Page:003
Big Book Catalog, Issue:67, Page:055
Law Enforcement / Police Store, Issue:13, Page:002
New Product Supplement, Issue:581, Page:001
Sinclair, Issue:4B, Page:221