The X-Act positioning base allows you to install posture aids while maintaining optimal levels of comfort and flexibility. ? Its frame is made of 90% aluminum for light weight (40 lb), making it easier for the caregiver to handle and just as easy for the user to propel. This base has a 250 lb capacity, but a special model is also available for heavyset individuals. The seat rails can accommodate a depth increase of 2" (5.2 cm) at any time and a decrease of 1" (2.2 cm) to 2" (5.2 cm) from a starting depth of 17" (43.2 cm). The tilt angle, controlled by two hydraulic cylinders, adjusts smoothly with two levers. Setting it at a negative 5° angle makes standing transfers easier. ?