Balanced Taper Gauges

Dear sir

I a using a taper gauge for verifying my synchronizer rings for taper diameter.Today i observed that these taper gauges are designed balanced i.e when i keep it on the surface plate it is balanced on the holding side and the checking side, i want to know that whether there is a specific reason to design it balanced.

I am also checking the run out on the components with it.

Regards

ankit