X2 (formerly known as X) is a steel roller coaster at Six Flags Magic Mountain in Valencia, California. It was the world's first fourth-dimension roller coaster and was the final roller coaster installed by ride manufacturer Arrow Dynamics. The ride is unique in that the trains' seats pitch 360 degrees forwards and in reverse independent of the main chassis. The coaster initially opened to the public on January 12, 2002; numerous issues delayed it from debuting in 2001 as was originally anticipated. On December 2, 2007, the ride closed for its transformation into X2. It was completely repainted, received new third-generation trains, and featured new special effects including onboard audio, fog effects, and a pair of flame throwers. The ride reopened on May 24, 2008, following the upgrades.

On December 19, 2000, Six Flags Magic Mountain announced that it would be adding three roller coasters for the 2001 season as part of a $30 million expansion: Déjà Vu, Goliath Jr. and the original X. This would bring the total to 15, beating the world coaster capital, Cedar Point. X was a prototype 4th Dimension roller coaster by Arrow Dynamics.

The ride was planned to open in the summer of 2001, but the opening was delayed when it suffered design flaws. X opened for passholders on December 24, 2001, and officially opened on January 12, 2002. A month before opening, Arrow Dynamics filed for Chapter 11 bankruptcy due to the ride's misjudged costs stemming from Six Flags asking for a much larger ride than Arrow had successfully prototyped (This is covered in the 2016 documentary The Legacy of Arrow Development). The manufacturer had lost millions of dollars on the project.

X was closed indefinitely in June 2002 due to issues with the trains. It was discovered that one of the coach seats that flipped riders was not moving smoothly. The ride reopened on August 13, 2002 after modifications were made to make it reliable.

On February 8, 2003, Super Bowl MVP Dexter Jackson took a ride on X as part of a victory celebration of the Tampa Bay Buccaneers football team.

On November 1, 2007, Six Flags Magic Mountain announced a redesign. X closed on December 2, 2007, to be redesigned including new trains with a pneumatic restraint system (an improvement over the original mechanically operated restraints that would frequently jam), a new color scheme of red track and black supports (originally pink track and yellow supports), and an all-new, innovative state-of-the-art visual, audio and sensory effects. In a projected $10 million investment, X reopened on May 24, 2008, as X2. Six Flags Magic Mountain hired S&S Arrow to build new trains for X2. The new trains are lighter to reduce the amount of wear and downtime. X2 also took on a new load/unload method and third train to increase the ride capacity by 50%. Testing of the trains began on March 6, 2008.

The attraction was closed in 2013 due to a broken chain lift. It reopened in January 2014 with only a single train.

The 3,610 ft (1,100 m) long layout features two inversions including a skydive, two "raven turns", one backflip, and a twisting front flip. Each car on the train spins on its own independent axis 360 degrees forward or backward, which is being controlled by the outer rails of the track. Unlike traditional roller coasters, 4th Dimension roller coasters like X2 have four rails.

After departing from the loading station, the ride makes a 180-degree turn traveling over the queue and onto the lift hill. After ascending 175 feet (53 m), the train enters a pre-drop and then ascends an additional 15 feet (4.6 m) to a maximum height of 190 feet (58 m). During this lift, riders are facing backwards. The first drop is 215 ft (66 m) and is sloped at 88.5 degrees, at the base of which ride vehicles attain a maximum speed of 76 mph (122 km/h).

During the initial drop, the seat assembly is rotated so that riders are positioned facing the ground. There is a pool of fog at the base of the drop, however this effect has not worked in many years. The train then enters an inside raven turn, where the cars are rotated again halfway through the loop to create a "lie-to-fly" maneuver; riders transition from lying on their backs facing backward to a prone position, facing forward. After exiting the raven turn, the trains traverse a hill, during which the seat assemblies rotate backward 360 degrees, simulating a backflip. This is followed by a sweeping fan turn and a half twist "fly-to-lie" maneuver, in which riders flip forward 180 degrees to return to the original position of laying on their backs. Flame throwing special effects can be seen overhead as the train enters an outside raven turn, with a brief pop of fog at the valley, immediately followed by another half twist. The track levels out and the train enters the final brake run before returning to the station.

X2 is a unique prototype design in which the seats can rotate forward or backward 360 degrees in a controlled spin. This is achieved by having four rails on the track. The two rails that control the spin of the seats move up and down relative to the main track and spin the seats using a rack and pinion gear mechanism. These "rotation" rails don't support the train. The other two rails are for the weight-bearing wheels, capable of supporting these heavy trains.

Weighing 5 t (4.9 long tons; 5.5 short tons), each vehicle has a wing-shaped design that spans 20 feet (6.1 m). Riders sit on the outside of the coaster track in pairs. Four, 1-foot (0.30 m) tall rack gears move up and down following the profile of the seat rotation rails below the vehicle. This gear rotates the seats forwards and backward throughout the ride.

The ride also has an on-board audio soundtrack that features five songs heard throughout the ride:

• Harry Connick Jr. - "It Had To Be You" (heard as the train exits the station)
• Portions of R. Lee Ermey's speech from Full Metal Jacket along with various movie quotes (heard on the lift hill)
• Metallica - "Enter Sandman" (heard on the lift hill)
• Aerosmith - "Love in an Elevator" (heard right as the train crests the first drop)
• Beastie Boys - "Sabotage" (heard throughout the ride)
• Rage Against the Machine - "Wake Up" (heard after the train hits the final brake run)

S&S Arrow opened the second roller coaster of this type, Eejanaika at Fuji-Q Highland in Fujiyoshida, Yamanashi, Japan. Eejanaika (a word with a complex social and political background in Japan) has several meanings, however, "Isn’t it great" or “Who cares” are some relevant meanings. This second 4th Dimension coaster is very similar to X2, but differs in height (Eejanaika is 250 feet (76 m) tall), and some elements are altered, such as the first 'half-half' element, in which the trains rotate on the track one half turn as the seats also rotate one-half turn, has now been replaced with a 'full-full' element, in which the train rotates on the track for one full turn as the seats rotate one full turn. The turn back towards the lift hill on Eejanaika is a true overbanked turn, while on X2 this turn was not. Dinoconda, a third 4th Dimension coaster, opened at Dinosaur Valley in Shanghai, China in May 2012.

Golden Ticket Awards: Top steel Roller Coasters

Year	2002	2003	2004	2005	2006	2007	2008	2009	2010	2011	2012	2013	2014	2015	2016	2017	2018	2019	2021	2022	2023	2024
Ranking	20	15	15	32	30	17	16	13	15	16	18	16	18	20	23	25	31	23 (tie)	26 (tie)	32	21	32 (tie)

• Official X2 page