Zhao Zhao has collected several steel safes from the colonial period of old Shanghai, some of which were fetched in by the colonist before, and the others were manufactured in Shanghai during that period. Repaired by the repairman, every steel safe can work appropriately, and Zhao Zhao has put his artworks or things related to himself in every steel safe. The keys were thrown into the Huangpu River after every steel safe were well locked. So far, the meaning of “keeping” the works or goods in those steel safe has become a “secret”.