The accuracy of your CNC machine depends on which kit you purchase and the calibration of the machine.
The Maslow CNC Basic Bundle and the Maslow CNC Jumpstart Kit use the manual adjustment screw on the base of the RIDGID router for the z-axis movement. These parts can become more worn over time, which affects accuracy.
The M2 has a dedicated z-axis motor assembly, which is much more sturdy than the manual adjustment screws on the base of the RIDGID router and allows for a much higher level of accuracy! Many users have been able to achieve an accuracy within 1mm with the M2!
Here is our table of compatible routers: https://makermade.com/router-recommendations/