Gemini² Dual Containment Tanks meet or exceed secondary containment regulations set under EPA 49CFR. These square tanks are designed with pump mounting surface, fittings per spec and 8" vented twist lid inspection port. Non-vented twist lid available. Recessed mouse door at bottom of tank for easy installation of bottom bulkhead for flooded suction draining. They have the same great features and benefits as the Gemini Dual Containment Tanks, but have larger capacity per footprint. They have 22% more capacity than cylindrical tanks of the same size.