I really don't know anything about these so I have attempted to take closeup photos of all sides.  I purchased a bunch of them from the estate sale of a friend's dad who was a Southwest aircraft mechanic.  They are vintage because he has been dead at least 20 years.  They did not sell his stuff until his wife died.  They are all brand new and I will be listing more sizes.  Please ask any questions you may have and I will try to get you an answer.

This one has the following markings on it.  M3Q5

If you make multiple purchases, I will be happy to combine shipping.  Just request an invoice before you pay.