The Vermont Gage steel go (+) plug gage is a class X inch gage for calibrating measuring equipment and gage parts. A certificate of accuracy traceable to NIST is available for each gage. All gages measure 2? long, and are within .00002? round (per ASME B89.1.5), with at least a 4-microinch finish for a smooth finish. Tolerance for this class X gage is +.000040? for sizes up to .825? and +.000060? from .8251? to 1.000?. This gage is made of tool steel 60/64 Rc (cold stabilized) for durability. Plug gages are precision ground cylindrical steel plugs used to measure the diameter and depth of drilled or machined holes. They are available in different classes, based on acceptable tolerance (allowed deviation from the stated size). Standard tolerances and classes for cylindrical gages up to .825? are as follows: Class XX (.00002" or .0005 mm), Class X (.00004" or .0010 mm), Class Y (.00007" or .0018 mm), Class Z (.0001" or .0025mm), and Class ZZ (.0002" or .0050 mm). For gages with a wider diameter, tolerance gradually increases for each class. Since 1968, Vermont Precision Tools, Inc. (VPT) has been manufacturing a variety of precision round and ground pins, perforators, and special punches. Vermont Gage was formed in 1980, and manufactures a wide range of fixed limit gages. Located in Swanton, Vermont and Franklin, Kentucky, Vermont Gage manufactures 98% of the products they sell and is ISO 9001:2000 and ISO 17025 quality certified.