The one you show looks like mine, purchased for the same from AAP. It was made by AMPro. I took it to work and had the calibration tech looked at it. It was accurate w/i 10% in the entire range.
My smaller AMPro, I think it is 10-80 ftlb with 3/8 drive, did worse. It was over torque by more than 10% at the lower half.
He just made me a table for setting vs. actual for it. He did not adjust it since it was non-linear.