Hello everyone, I know this will most likely be a long shot but I've exhausted my other options. Owner of my company purchased a Brencor 60° center chek (model 650, please see attached pictures) at auction with some other gauges and odds and ends but it didn't come with the master ring for calibration and that's what it says to 'set to' on the back of the gauge. It appears Brencor is no longer a company, and I've looked everywhere I can think of online, including contacting a few companies that sell Brencor gauges but they all tell me that the gauge I have they no longer support. Does anyone have any info on the master ring dimensions, or can possibly tell me what theirs reads on a flat surface? Thank you!