The 3D-Tasters are very cool. You put the ball against the edge you want to zero (X, Y or Z) and move that axis. When the needle points to zero, hit zero in Mach and go to the next axis. Very much a luxury over a standard edge finder with the subtracting and adding diameters, but one I find highly useful. The only irritation about mine (an eBay special) is the 20mm shank which required me to make an adapter.