 The first discs were therefore housed in cartridges for protection, resembling Professional Discs introduced by Sony in 2003.Using a cartridge would increase the price of an already expensive medium, and would increase the size of Blu-ray disc drives, so designers chose hard-coating of the pickup surface instead.TDK was the first company to develop a working scratch-protection coating for Blu-ray Discs, naming it Durabis.