Models that support a more forgiving RF dongle, like the ones with Logitech's Unifying technology, can work using a replacement dongle or another device's dongle. The dongles are often keyed to the specific keyboard you own, so losing one can mean the keyboard is out of commission for good. Some keyboards have a storage slot for their dongles, which is great, but it's still a tiny part you need to keep track of.
And because a USB dongle is an extra part, you can lose it if you often swap it between systems or carry your keyboard around. No desktop or laptop has built-in support for these keyboards you need that USB dongle. In modern keyboards, 2.4GHz RF offers a stable connection and, at times, a near-imperceptible amount of typing lag. Each connection type offers distinct advantages and disadvantages. The latter connects to your device via a USB dongle Bluetooth models assume your host computer supports Bluetooth, or you have your own Bluetooth dongle. Wireless keyboards (and wireless mice, too) use two primary technologies to connect to devices: Bluetooth, or a 2.4GHz radio-frequency (RF) connection.
