There are three types of pin gauges. Plus, Minus, and Master sets.
Plus and minus sets are used to create Go/No-Go scenarios. The plus pins are slightly above the nominal size to create a no-go in relation to the target dimension. The minus pins are slightly below the nominal size to create a go scenario in relation to the target dimension.
An 11mm pin will not fit in an 11mm hole. You would choose an 11mm minus pin to verify.

Master pin gauges are machined as close to the nominal size as possible and do not lean one way or another (at least within its listed tolerance).

Your set having the + on it makes it a plus pin gauge set. They are all slightly larger than the listed nominal size.

As far as the T11 labeling... I am not entirely sure. I am currently surrounded by a library of about 5,000 pin gauges and they all have that style alpha-numeric stamping. I see B51, L18, A19, U26, Q69, B86, L40, P54.... and I cannot find any rhyme or reason to it. It does not seem to be associated with the size/tolerance of the gauge in any way. Only thing I can think of is it is some kind of serial number or possibly the machine/operator that made it? If anyone knows the answer, I am curious. It has bugged me for many years, but never bothered to look into it.

The classes are (lowest to highest tolerance) ZZ, Z, Y, X, XX, XXX. These define the tolerances and should be listed on the gauges or at least on the box they came in. The exact tolerance depends on the class and size. There are charts available to tell you what the exact tolerance for a specific pin size is.

Below is one of my gauges:
This is a Meyer, Class Z, 0.249", Plus pin gauge.
It has a nominal size of .249", but actually measures 0."
Its listed tolerance is +/- ."
No clue what the B51 means, could be a "unique identifier". This would be handy when dealing with these large pin libraries, but not sure why it isn't sequential...

Hey there,There are three types of pin gauges. Plus, Minus, and Master sets.Plus and minus sets are used to create Go/No-Go scenarios. The plus pins areabove the nominal size to create a no-go in relation to the target dimension. The minus pins arebelow the nominal size to create a go scenario in relation to the target dimension.An 11mm pin will not fit in an 11mm hole. You would choose an 11mm minus pin to verify.Master pin gauges are machined as close to the nominal size as possible and do not lean one way or another (at least within its listed tolerance).Your set having the + on it makes it a plus pin gauge set. They are all slightly larger than the listed nominal size.As far as the T11 labeling... I am not entirely sure. I am currently surrounded by a library of about 5,000 pin gauges and they all have that style alpha-numeric stamping. I see B51, L18, A19, U26, Q69, B86, L40, P54.... and I cannot find any rhyme or reason to it. It does not seem to be associated with the size/tolerance of the gauge in any way. Only thing I can think of is it is some kind of serial number or possibly the machine/operator that made it? If anyone knows the answer, I am curious. It has bugged me for many years, but never bothered to look into it.The classes are (lowest to highest tolerance) ZZ, Z, Y, X, XX, XXX. These define the tolerances and should be listed on the gauges or at least on the box they came in. The exact tolerance depends on the class. There are charts available to tell you what the exact tolerance for a specific pin size is.Below is one of my gauges:This is a Meyer, Class Z, 0.249", Plus pin gauge.It has a nominal size of .249", but actually measures 0."Its listed tolerance is +/- ."No clue what the B51 means, could be a "unique identifier". This would be handy when dealing with these large pin libraries, but not sure why it isn't sequential...

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Standard Steel & Black Guard Gages&#;

Vermont Gage stocks Class ZZ gages in both Steel and Black Guard. The Class X gage pins are stocked in both the Plus and Minus direction of tolerance in ." increments.

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