Checking focuses mainly on the influence of component errors (CMM geometry). Before the use of Bridge-Check, the probe system must also be checked which can be accomplished using Probe-Check or CMM-Check. The two-dimensional artifact (multi-sphere test standard - MSTS) consists of a steel plate featuring 25 inner sphere elements (highly precise ball bearing outer rings) in a regular grid pattern. The MSTS can be used on CMMs from all manufacturers.