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What is the difference between a Class ZZ and a Deltronic Gage?

If you can let us know; what is the difference between Class zz and deltronic gage? Which is more accurate?
Please suggest as we have to measure hole between 0.251"-0.2525" for production gaging.

Q A Manager  

Reply from:
A Class ZZ tolerance for the diameter range .006 - .825 is .0002" (.005MM).
Deltronic makes Class X Plus tolerance, for the diameter range .006 - .825 is .000040" (.001mm).
The suggested tolerance for your product is Class Y (.000070"). This is based on the 10% rule, that the gages may not use more than 10% of the total product tolerance.
See our free Tolerance Calculator & Tolerance chart from ASME B89.1.5 at
We would not suggest using Class ZZ gages for this product. We do Stock Class X gages.

Subject: Re: Inquiry

Thanks a million Mike .You have always provided us with useful information.
We thank you from the bottom of our heart for all your help.