| Fourth-dimension roller coaster | |
|---|---|
 'X²' (formerly 'X') was the first fourth-dimension roller coaster in the world. | |
| Status | In production |
| First manufactured | 2002 |
| No. of installations | 18 |
| Manufacturers | Arrow Dynamics (discontinued), S&S Worldwide, and Intamin |
| Riders per row | 4 |
| Restraint Style | Over-the-shoulder |
A fourth-dimension roller coaster is a type of steel roller coaster where riders are rotated independently of the track's orientation, generally about a horizontal axis perpendicular to the track. The cars do not need to be fixed to an angle.