2 units not purchased for each 20.11. Massive problems with CD-RW (with blanks Verbatim and whether 4x od. 10x). Same blanks without any problems with the same firing program in Plextor / ASUS / LG. Also act. Firmware Update (12/2013) does not solve the problem. Contact with manufacturer Hotline without any reaction. Goodwill, thanks Amazon.