When sourcing a double puller, you must prioritize synchronization accuracy and traction force. Ensure the machine features high-precision servo motor drives to maintain consistent tension, preventing profile deformation. Key specs include the maximum extrusion speed (m/min), clamping force, and the effective stroke length which must align with your extrusion press capacity. Look for linear guide rail systems for smooth movement and PLC control systems (e.g., Siemens or Mitsubishi) for seamless integration with the press.