The REL-K (Rizzoli Electronic Knee), distributed by Fillauer, is the latest generation of microprocessor knees, giving patients who have undergone amputation the ability to easily navigate their environment. With six modes of control, patients can walk, run, negotiate slopes, climb stairs, or ride a bicycle. Since the control system is located proximally, most foot and pylon combinations can be used. The knee’s composite frame was developed by Italian sports car designers for strength and cosmetic appeal and its hydraulic unit evolved from a Formula One design used for speed and control. The REL-K is rated for patients up to 220 lbs.