The T-11 is the most popular adult shape and the one most often used by professional karting teams and manufacturers. With every generation growing taller, a new seat was needed. A large flat area on the base was created and combined with a more reclined back angle of 58°, lowering the head height significantly. Whilst lowering the body weight gives a performance advantage, it is important to maintain an upright shoulder position to allow enough power to be transferred to the steering. The driver is likely to "pull to steer” if they are too reclined, which is bad for handling and body stability. The T11 shape enables the correct upper torso angle to retain firm control and therefore performance.