Inside diameter tolerance of 0.0004", Trubore, a trademark of Ace Glass Incorporated, stands for precision bore tubing of the highest quality, maintained by production techniques, careful selection of raw materials, and step-by-step quality control. Trubore tubing is used in ACE items such as our Trubore Stirrers and McLeod Gauges. See codes -90 thru -97 for our square precision tubing.