This Toshiba Tablet PC Reserve Pen is designed to work with your Toshiba Satellite R10, R15, Portege M200, M205 series Tablet PCs and Tecra M4 in case of an emergency situation. Compared to the PC pen that was included with your Tablet PC, this reserve pen is smaller and can be stored next to a main battery inside the computer. So in case you lose the regular Tablet PC pen, you can still input using the reserve pen until the regular PC pen is relocated or replaced.