I'm a bit worried about the accuracy because the metal wheel underneath the ruler is a bit loose.
I tried the calliper on a known measurement, and it was a bit off each time. The calliper changed the measurement when it was tilted, sometimes accurately, sometimes not.
When the jaws are closed after measuring they don't always return to zero unless the rest button is pressed.
It's well protected with 2 extra batteries, but may not be useable if not accurate. :- (