The Truncated setting plug gage is designed for two functions; to calibrate and set an adjustable thread ring gage, and to inspect the ring gage for wear. Truncated set plugs have a common pitch diameter the full thread length of the GO or NOGO section. The crest of the thread is truncated in diameter for the first half of the set plug and "full form" the remaining length. The truncated section is used to set the pitch diameter and the full form is used to detect flank angle problems or undersize major diameters in the thread rings.

Truncated set plug gages are manufactured to ASME/ANSI B47.1 AGD standard and are ASME/ANSI B1.2, ANSI/ASME B1.16M compliant. WESTport truncated set plug gages are manufactured to the highest end of the ANSI specifications to ensure the longest gage life possible. The truncated set plugs are held to Class W tolerances on lead, flank angles and straightness (taper) and to Class X tolerance for pitch diameter for inch and to Class 6g class of fit for pitch diameter for metric. Class W tolerance for pitch diameter quoted upon request. Truncated set plug gages are available in steel and chrome.

WESTport Gage manufactures special plug and ring gages including oversize pre-plates, miniature thread gages, multiple starts, special leads, acme threads, buttress threads, square threads, extra length thread gages, and blue print specials. WESTport Gage provides a Certificate of Accuracy, traceable to NIST (National Institute of Standards and Technology), free of charge with every truncated set plug gage.