Oak Street High Density Storage is a facility which specializes in preserving materials. The climate is controlled by air-conditioning to keep the ideal temperature and humidity level for maintaining the materials (about 50? Fahrenheit and 30% humidity). I was surprised that they are sorted and separated by their size, but it is efficient way to save the limited spaces. Although, low circulation items are sent to this facility, their patrons can request items through the online catalog and many of the materials stored in the storage are also available digitally. It was a good experience for me to visit such a specialized facility.