Digital Audio Tape (DAT or R-DAT) is a signal recording and playback medium developed by Sony in the mid 1980s. In appearance it is similar to a compact audio cassette, using 4 mm magnetic tape enclosed in a protective shell. As the name suggests the recording is digital rather than analog, DAT converting and recording at higher, equal or lower sampling rates than a CD (48, 44.1 or 32 kHz sampling rate, and 16 bits quantization). If a digital source is copied then the DAT will produce an exact clone, unlike other digital media such as Digital Compact Cassette or non-Hi-MD MiniDisc, both of which use lossy data compression.