which some users have replaced themselves. Unibody (2008–2011) On October 14, 2008, in a press event at company headquarters, Apple officials announced a new 15-inch MacBook Pro featuring a "precision aluminum unibody enclosure" and tapered sides similar to those of the MacBook Air. Designers shifted the MacBook Pro's ports to the left side of the case, and moved the optical disc drive slot from the front to the right side, similar to the MacBook. The new MacBook Pro computers had two video cards that the user could switch between: the Nvidia GeForce 9600M GT with either 256 or 512 MB of dedicated memory and a GeForce 9400M with 256 MB of shared system memory. The FireWire 400 port was removed. The DVI port was replaced with a Mini DisplayPort receptacle. The original unibody MacBook Pro came with a user-removable battery; Apple claimed five hours of use, with one reviewer reporting results closer to four hours on a continuous video battery stress test. Apple said that the battery would hold 80% of its charge after 300 recharges. The unibody-construction MacBook Pro largely follows the styling of the original aluminum iMac and the MacBook Air and is slightly thinner than its predecessor, albeit wider and deeper due to the widescreen display. The screen is high-gloss, covered by an edge-to-edge reflective glass finish, while an anti-glare matte option is available in the 15- and 17-inch models in which the glass panel is removed. The entire trackpad is usable and acts as a clickable button. The trackpad is also larger than that of the aluminum models, giving more room for scrolling and multi-touch gestures. When the line was updated in April 2010, inertial scrolling was added, making the scrolling experience much like that of the iPhone and iPad. The keys, which are still backlit, are now identical to those of Apple's now-standard sunken keyboard with separated black keys. The physical screen release latch from the aluminum models is replaced with a magnetic one. During the MacWorld Expo keynote on January 6, 2009, Phil Schiller announced a 17-inch MacBook Pro with unibody construction. This version diverged from its 15-inch sibling with an anti-glare "matte" screen option (with the glossy finish standard) and a non user-removable lithium polymer battery. Instead of traditional round cells inside the casing, the lithium-ion polymer batteries are shaped and fitted into each notebook to maximally utilize space. Adaptive charging, which uses