Prior's PS3H122R bolt-on motorized focus drive is compatible with Zeiss Axioimager, Axioskop, and Axiovert microscopes. See the product compatibility tab for details. 

The unit clamps directly to the coarse focus knob and assumes control over the fine focus, having sufficient resolution to maintain the step resolution of the manual focus drive it is attached to. 

Installation is simple and does not require the microscope body to be inverted or disassembled. Simply clamp the PS3H122R onto the focus drive and push it onto the fine focus knob. Additionally, some microscopes allow the PS3H122R to be directly coupled to the fine focus drive, enhancing repeatability. 

Compatible with Prior's 3-axis OptiScan^® and ProScan^® controllers, and single-axis ES10ZE, the PS3H122R represents a simple method of enabling automated Z-stacking, extended focus and autofocus operations on manual microscopes.