DisplayPort 1.0–1.1a allow a maximum bandwidth of 10.8Gbit/s (8.64Gbit/s data rate) over a standard 4-lane main link. DisplayPort cables up to 2 meters in length are required to support the full 10.8Gbit/s bandwidth. DisplayPort 1.1 allows devices to implement alternative link layers such as fiber optic, allowing a much longer reach between source and display without signal degradation, although alternative implementations are not standardized. It also includes HDCP in addition to DisplayPort Content Protection (DPCP). The DisplayPort1.1a standard can be downloaded for free from the VESA website. 1.2 DisplayPort version 1.2 was introduced on 7 January 2010. The most significant improvement of this version is the doubling of the data rate to 17.28Gbit/s in High Bit Rate 2 (HBR2) mode, which allows increased resolutions, higher refresh rates, and greater color depth, such as at 60Hz 10bpc RGB. Other improvements include multiple independent video streams (daisy-chain connection with multiple monitors) called Multi-Stream Transport (MST), facilities for stereoscopic 3D, increased AUX channel bandwidth (from 1Mbit/s to 720Mbit/s), more color spaces including xvYCC, scRGB, and Adobe RGB 1998, and Global Time Code (GTC) for sub 1μs audio/video synchronisation. Also Apple Inc.'s Mini DisplayPort connector, which is much smaller and designed for laptop computers and other small devices, is compatible with the new standard. 1.2a DisplayPort version 1.2a was released in January 2013 and may optionally include VESA's Adaptive Sync. AMD's FreeSync uses the DisplayPort Adaptive-Sync feature for operation. FreeSync was first demonstrated at CES 2014 on a Toshiba Satellite laptop by making use of the Panel-Self-Refresh (PSR) feature from the Embedded DisplayPort standard, and after a proposal from AMD, VESA later adapted the Panel-Self-Refresh feature for use in standalone displays and added it as an optional feature of the main DisplayPort standard under the name "Adaptive-Sync" in version 1.2a. As it is an optional feature, support for Adaptive-Sync is not required for a display to be DisplayPort 1.2a-compliant. 1.3 DisplayPort version 1.3 was approved on 15 September 2014. This standard increases overall transmission bandwidth to 32.4Gbit/s with the new HBR3 mode featuring 8.1Gbit/s per lane (up from 5.4Gbit/s with HBR2 in version 1.2), for a total data throughput of 25.92Gbit/s after factoring in 8b/10b encoding overhead. This bandwidth is enough for a 4K UHD display () at 120Hz with 24bit/px RGB color, a 5K display () at 60Hz with 30bit/px RGB color, or an 8K UHD display () at 30Hz with 24bit/px RGB