Hello Mike, The paper work on the mast I have states .120 wall thickness and has a Yield Strength of 106,442 psi. I hope that helps. 73, Jack W4NF -- FAQ on WWW: http://www.contesting.com/towertalkfaq.html Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: owner-towertalk@contesting.com Search: http://www.contesting.com/km9p/search.htm