Original Logitech USB Receiver for Logitech MX 5500 Revolution M/N Y-RBF91 (Keyboard), M-RCL124 (Mouse) Brand New Original Logitech Receiver (993-000141) for Logitech Cordless Desktop MX 5500 Revolution This Receiver will work Only With M/N Y-RBF91 (Keyboard), M-RCL124 (Mouse) The part number on the bottom of the keyboard must match this number 820-000814