This Wei T'o Book Dryer and Insect Exterminator performs two functions: freeze-drying and extermination freezing to eradicate insects. Procedures for the two differ. For freeze-drying wet books or papers, the idea is to keep the temperature as warm as possible but still below freezing, and to keep air constantly moving within the freezer. This is accomplished by built-in compartment fans. Extermination freezing involves subjecting the items to freeze/thaw cycles with the freezer set to subzero temperature.