USGI - Mil-Spec - government contract mags. Manufactured in Connecticut by Okay Industries. Okay Industries has been producing M16 magazines for the US Gov't for over 35 years. There are many companies advertising their magazines to be be milspec or USGI equivalent, however, these companies do not have a government contract, and have actually failed government testing for durability as well as reliability. While these magazines are not of the lowest price, they are of the highest quality.  Buy with confidence.