Hi Flintstone! The Pro differed from the CZ7a mainly because they changed the configuration of the machine. They put a pistol grip and put the 2 9V batteries in the control box, instead of the S rod with the AA batteries mounted under the arm cup. The Pro is a bit lighter, but ergonomically, most folks favored the better balancing of the CZ7a. However, the CZ7a Pro could be hip mounted with the belt clip that was supplied with the detector, so that was a plus. Operationally, there was no difference and both are great units. As Dan said above, google Mike's CZ page for lots of good info. These units are tough to beat if you are searching a wet salt beach, and CZ's of all models are known to love silver!