SKS Zytel magazines... all made in the USA?

[Diggler]

I am working on getting my Chicom SKS to the point that I don't have to worry about 922 anymore. I have an old Zytel magazine that has NO markings anywhere on it. Not sure of the brand, but I don't think I've ever seen Zytel that was made by any foreign companies. Am I safe to assume that it is a US magazine?