Only one of the mags has the Cobray marked base plate, the others are just plain but as far as I can tell they are all the same. 

COBRAY, SWD, MAC, RPB, Leinad, Military Armament Corporation, M10, M11, M11a1, M12, m-10, m-11a1, 
m-11, m-12, Scionics, Ingram, Marietta, Atlanta, Powder Springs, Ducktown, Stevensville. Norinco  SKS Type 56