When sourcing a PU mix head, you must prioritize mixing efficiency and pressure ratings. High-pressure mix heads typically operate between 150 to 200 bar to ensure impingement mixing, while low-pressure versions use mechanical stirrers. Key specs include the output range (g/s), the number of components (2-stream or multi-stream), and the cleaning mechanism (e.g., hydraulic piston cleaning vs. solvent flushing). Ensure the head is compatible with your specific chemical viscosity and temperature requirements.