Various Types of Logitech Receivers (software links in description) - YouTube
Amazon.com: Logitech USB Unifying Receiver - Black : Electronics
Amazon.com: Logitech USB Unifying Receiver - 2 Pack For Personal Computer : Electronics
Wireless Dongle Receiver Unifying USB Adapter for logitech Mouse Keyboard Connect 6 Device for MX M905 M510 Keyboard K400
Amazon.com: Logitech Unifying Receiver, 2.4 GHz Wireless Technology, USB Plug Compatible with all Logitech Unifying Devices like Wireless Mouse and Keyboard, PC / Mac / Laptop - Black : Electronics
Unifying Receiver Keyboard - Best Buy
Amazon.com: Logitech USB Unifying Receiver - 2 Pack For Personal Computer : Electronics
Logitech MK825 Palm Rest Wireless Keyboard K850 and M585 Mouse Combo, Recertified | MPD Mobile Parts & Devices - Motorola Authorized Distributor
Logitech Unifying Receiver for Connecting Multiple Devices