Features & details ERGONOMIC WAVE DESIGN – The MK550 uses Logitech’s Constant Curve layout for reduced stress and better, more natural typing. The layout is familiar, so there is little to no learning curve to begin using it fluidly INTEGRATED PALM REST – Experience lower wrist fatigue with the integrated palm rest , Three options for leg height allow you to adjust the keyboard to the height that feels most comfortable to you. K350 keyboard has a battery life of up to 3 years, and the mouse, up to 2 years, with 2 standard AA batteries in each device NEW IN BOX. Never used.