The Benchmark Scientific B4000-28-120 BioClave 28 Research Autoclave, 28 liter, 120V is designed specifically for the sterilization of laboratory research tools. The B400028120 include a mechanical and electrical safety interlock that prevents the door from being opened until the pressure has reached zero PSI. The B400028120 is fully automatic operation with a large digital LCD display. The B400028120 features an increased chamber size with a diameter of 32cm. The B400028120 is only model capable of sterilizing 1 and 2 liters flasks (and bottles).