with markers in tests. HD DVD uses traditional material and has the same scratch and surface characteristics of a regular DVD. The data is at the same depth (0.6 mm) as DVD as to minimize damage from scratching. As with DVD the construction of the HD DVD allows for a second side of either HD DVD or DVD. A study performed by Home Media Magazine (August 5, 2007) concluded that HD DVDs and Blu-ray discs are essentially equal in production cost. Quotes from several disc manufacturers for 25,000 units of HD DVDs and Blu-rays revealed a price differential of only 5-10 cents. (Lowest price: 90 cents versus 100 cents. Highest price: $1.45 versus $1.50.) Another study performed by Wesley Tech (February 9, 2007) arrived at a similar conclusion. Quotes for 10,000 discs show that a 15 gigabyte HD DVD costs $11,500 total, and 25 gigabyte Blu-ray or a 30 gigabyte HD DVD costs $13,000 total. For larger quantities of 100,000 units, the 30 gigabyte HD DVD was more expensive than the 25 gigabyte Blu-ray ($1.55 versus $1.49). While there is a HD-DVD variant that acts as a successor for the DVD-RAM, the HD DVD-RAM, a "BD-RAM" has never been released. Although the BD-RE has unrestricted random writing access capabilities, its rewrite cycle count of around 1000 times is much lower than the potential 100.000 rewrite cycles of some DVD-RAM variants. Hybrid discs At the Consumer Electronics Show, on 4 January 2007, Warner Bros. introduced a hybrid technology, Total HD, which would reportedly support both formats on a single disc. The new discs were to overlay the Blu-ray and HD DVD layers, placing them respectively and beneath the surface. The Blu-ray top layer would act as a two-way mirror, reflecting just enough light for a Blu-ray reader to read and an HD DVD player to ignore. Later that year, however, in September 2007, Warner President Ron Sanders said that the technology was on hold due to Warner being the only company who would publish on it. One year after the original announcement, on 4 January 2008, Warner Bros. stated that it would support the Blu-ray format exclusively beginning on 1 June 2008, which, along with the demise of HD DVD the following month, ended development of hybrid discs permanently. Copy protection The primary copy protection system used on both formats is the Advanced Access Content System (AACS). Other copy protection systems