I am trying to understand everything I can about some stainless-steel nuts that I have come across. I have already researched and found information on the characters at the bottom of each nut, but I cannot find information on the symbol that looks like Theta at the top. So, my question is,

What does the ~Theta symbol mean on these stainless-steel nuts?

enter image description here

1 Answer 1


I'd have to guess it's the manufacturers' logo.

In addition to the indicated grade marking, all grades, except A563 grades O, A and B, must be marked for manufacturer identification. –americanfastener.com

  • I think you have a Fxxx grade D nut, so no, the identification rule applies. "all grades except...". The keyword Theta yielded me little results amongst fastener companies.
    – Mazura
    Commented Jul 16, 2015 at 1:43
  • 1
    Apologies for removing my note that you replied to. Anyway, I think you are correct that it is not a Theta symbol; I found this 'fastener identification guide' that may be helpful to future readers: idot.illinois.gov/Assets/uploads/files/Doing-Business/… It has a company symbol on page ~42 for a company named 'MNP Manufacturing Corp.' that I think may be a match.
    – John R
    Commented Jul 16, 2015 at 1:51
  • Finding an actual picture of a MNP bolt, clearly showing its markings is proving difficult. I'm going to go ahead and say, sure ;p –Nice link for identifying manufacturers.
    – Mazura
    Commented Jul 16, 2015 at 2:04
  • Same here. I also tried the same strategy , but have not found one in Google images. Btw, Thanks!
    – John R
    Commented Jul 16, 2015 at 2:11
  • If anyone is following this, I emailed MNP and they responded, "MNP does not manufacture nuts."
    – John R
    Commented Jul 17, 2015 at 0:39

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