> For the complete documentation index, see [llms.txt](https://wiki.inels.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://wiki.inels.com/inels-home/inels-wireless/devices/system-units.md).

# System Units

Gateways and system units that connect iNELS Wireless to the app, the cloud and higher automation.

*Part 3 — Unit reference.*

Transmitters and receivers already work together after [direct pairing](/inels-home/inels-wireless/pairing-and-configuration.md). **System units** add what direct pairing cannot do: control from the **app or cloud**, **scenes, timers and schedules**, and **logic and automation** that links different devices.

| Unit         | What it is                                                      | Page                                                                                                          |
| ------------ | --------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------- |
| **eLAN-204** | Smart gateway — RF units to app, web interface and cloud        | [eLAN-204](/inels-home/inels-wireless/devices/system-units/elan-204.md)                                       |
| **eLAN-103** | Smart gateway (LAN; Wi-Fi in the Wi-103 version)                | [eLAN-103](/inels-home/inels-wireless/devices/system-units/elan-103.md)                                       |
| **RFTC-3**   | Glass thermostat for fan coils; also works as a system unit     | [RFTC-3](/inels-home/inels-wireless/devices/inels-wireless-heating-temperature-control/thermostats/rftc-3.md) |
| RF Touch-2   | Flush-mounted wireless touch unit; also a communication gateway | [RF Touch-2](/inels-home/inels-wireless/devices/system-units/rf-touch-2.md)                                   |
| RFRP-20N     | Repeater — extends the radio range                              | [RFRP-20N repeater](/inels-home/inels-wireless/devices/system-units/rfrp-20n-repeater.md)                     |

**How to add already-paired devices to a gateway:** [Adding paired devices to a gateway](/inels-home/inels-wireless/devices/system-units/adding-paired-devices-to-a-gateway.md) · overview: [Tutorial 9](/inels-home/inels-wireless/tutorial-9-adding-a-gateway.md).

{% hint style="info" %}
**Do I need a gateway?** Not to switch a light with a wall button — that is direct pairing and needs no network. You need a gateway when you want the app, the cloud, or automation. See [Transmitters, receivers and gateways](/inels-home/inels-wireless/transmitters-receivers-and-gateways.md).
{% endhint %}

**Typical use.** Pair the buttons and detectors directly to the actuators (so the lights always work), then add the same devices to the gateway for the app and automation.