We frequently get inquiries for calibration services or calibration certificates from Omega Engineering. While some series from them do come with certificates of calibration included, this is on a case by case basis and not all of their devices come with such documentation. This will always be clarified in the datasheet for a given sensor however, so it’s relatively easy to double check.
If you have an Omega Engineering/Dwyer part that is in need of traceable calibration, the good news is that they do offer calibration services. Here’s the landing page for Dwyer/Omega’s calibration options: https://www.dwyeromega.com/en-us/calibration-services