Autoclave Sterilizer

What is the difference between Class N and Class B autoclave sterilizer?
1. Class N is autoclave without pre-vacuum function. The letter "N" stands for "naked solid products". It's mainly use to sterilize solid instruments.
2. Class B sterilizers, also called pre-vacuum steam sterilizers, they have a pump that creates a vacuum in the chamber to ensure air is removed from the sterilizing chamber before steam enters. The advantage is that there is faster and more thorough steam penetration throughout the entire load.
3. Class B will make the sterilization of wrapped hollow instruments more complete.