1,Flat bottom ground flask(chemistry flask) 2,High temperature resistance and ... ,, 500,, 1000,, 2000,, 3000,, 5000,, 10000,, 20000,, 50000 joint:14/20,,14/25,,19/22,,19/28,,24/30,,24/40 ... :for scientific research, teaching, medicine, and petroleum chemical industries. glass flat bottom flask(chemistry flask)