How to choose 2 phase or 3 phase? Answer: Check your Y aixs stepper motor driver. If there is Port of A+, A-, B+, B- on it, please choose 2 Phase. If there is port of U, V ,W on it,please choose 3 Phase. Features: Engraving Diameter: 10mm-150mm Engraving length: 50mm-350mm This CO2 laser engraving machine roller rotary shaft can add rotary laser processing capability to your laser engraving cutting machine. It's eazy to resize for a variety of round products such as cylindrical glasses, mugs, bottles and so on. Our four-wheel swivel attachment is ideal for engraving cylindrical objects with laser engraving machines.