8.1.4.2 The mechanical dimension of CDs and DVDs are equal: 120mm in diameter, and
1.2 mm thick. The DVD, however, is made up of two discs of 0.6mm thickness, which are bonded together. 8.1.4.3 CD-R and DVD+R consist of three layers: the clear polycarbonate substrate, the dye layer and the reflective layer.
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