APOLLO Stainless Expansion TankAPOLLO Stainless Expansion Tank 6. 5 9. 5 Gal High quality expansion tank designed to protect hydronic heating and cooling systems by absorbing excess pressure and maintaining system stability, ensuring long term performance and reliability. Key Benefits Maintains stable system pressure to prevent damage and extend equipment lifespan Absorbs thermal expansion for safe and efficient operation Durable 316 stainless steel construction for corrosion