When sourcing a used line, you must prioritize the mechanical condition of the double-belt conveyor (caterpillar) and the precision of the metering pumps. Ensure the line supports the specific core materials you need, such as PU (Polyurethane), PIR, or Rockwool. Key specs include the effective production speed (m/min), the maximum and minimum panel thickness (typically 50mm-250mm), and the width adjustment range. Verify if the PLC control system is a recognizable brand like Siemens or Mitsubishi to ensure future software support and spare parts availability.