I think this one is the best on the market today. (Posted on 24 July 2015)
Why Do I Need a Calibration Certificate?
Calibration and annual calibration is an important part of your maintenance and quality records as it acts as your evidence of compliance. All testers are calibrated as standard when they are produced by the manufacturer, however, sometimes a Calibration Certificate is not issued.
We recommend all new testers are calibrated at the date of purchase to ensure a full 12 months coverage in your name. Not only this, but it ensures the tester you are purchasing is functioning correctly before you receive it.
What is a Certificate of Conformity?
Sometimes a manufacturer issues a Certificate of Conformity, but this is not a Calibration Certificate
A certificate of conformity refers to a document that certifies that the supplied services or goods meet required specifications. It is normally issued by a competent authority and is also known as the certificate of compliance.