I bought Z-axis Unit for Eleksmaker A3 Pro, and once assembled into it.
Actually, it DID work well, and I think it's very good item.
But currently I remove the unit after 1month since I assembled for some reasons.
1.It's heavy, the laser module slipped(rotated) on x-axis, and I had to thighten screws.
2.The Z-axis unit reduced Y-Axis area about 80-100mm.
3.I thought it should be useful when I cut thick MDF board, but I didn't need it.
I do NOT suggest use Z-axis module for moving laser unit, because you may NOT need to move laser module in z-axis.