ah ok mate.... i bought this one secondhand a few years ago and it never had one, the bloke i bought it off sold it to me because he had never used it!!

it never came with a certificate.

Also meant to say i did check it against my other digital torque wrench and set them both to the same torque setting and the light came on at the correct torque!! if you were interested and did buy it then werent happy with it you could return to me for a refund... cant say fairer than that