Thread ring gage designtion

I am doing and inventory of our thread gages and have come across several odd gages. They have a -2 on the end of the size. For example: 1 1/8-12
NF-2. It's on the GO and the NO-GO ring. The pitch diameter is slightly larger on these -2 ring gages than on the standard gages. Couldn't find any info in the Machinery Handbook. Can anyone explain these?
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NF stands for National Fine also called UNF Unified National Fine So my guess is your 1 1/8-12 UN-2 is the same as 1.125-12 UNF-2A.
If the PD is not within 2A tolerance for each member then the gauge is out of tolerance or it is a mislabeled special.
-- Tom http://tinyurl.com/5okkgz
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? 2009?7?26???? UTC +8??12:06:31?DrFrye???

any

I Think it is 1 1/8-12 UNF-2A or 2B if you need new gage, try this http://www.gaugestools.com/un-thread-gauges/
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