Bruno Coelho explain the DiffCheck

The most beautiful and versatile device for Diff measurement in the world!
100% Autonomous with 9V Battery
DiffCheck Plus can be powered by the internal battery that allows its use without having to connect to any external power supply. However, it is equipped with an input that allows external power supply. The battery chosen to power the DiffCheck Plus is a common 9V Alkaline in order to make it possible to transport travelling by plane.
Design made in Italy
To guarantee the highest quality standard, Diff Check Plus is entirely developed in Italy. The case of the “DiffCheck Plus” is made from a solid piece of aluminum completely machined to accommodate the best components in the least possible space without neglecting ergonomics.