[COMPACT 50mm CALIBER] Small diameter allows for longer storage and cycle, while large diameter will cause liquid nitrogen leakage. [AEROSPACE MATERIALS] The liquid nitrogen container is made of high-strength aerospace aluminum material, which is corrosion-resistant and can store liquid nitrogen safely. [EXCELLENT PRODUCTION PREOCESS] Optimized design process, aviation paint, less welds, beautiful, low temperature resistance. [PLEASE NOTE] Due to air traffic control, we will only send you empty liquid nitrogen tanks.