A view of the inner layers of the cryostat with two towers installed. Detector towers are mounted in the holes covered by hexagonal plates. The coldest part of the cryostat stays at 10 mK (millikelvin, or thousandths of a degree above absolute zero) during operation. The surrounding layers are higher temperature stages of the cryostat. The cryostat is constructed using radiopure copper to provide a low-radioactivity environment for the extremely sensitive CDMS detectors.