When sourcing used machinery, you must prioritize the mechanical condition and production capacity. Key specs include the maximum and minimum sheet size the machine can handle, the number of printing colors (if it is a Flexo Folder Gluer), and the rated production speed (e.g., sheets per hour). Ensure the slotting and die-cutting precision meets your requirements, typically within a ±0.5mm to ±1mm tolerance. Additionally, verify the flute type compatibility (A, B, C, E, or double-wall) to ensure it aligns with your current cardboard stock.