Temperature sensors

A dedicated temperature sensor is what you use for a freezer, a crawlspace, or a room your thermostat cannot feel. The spec to check is the operating range, because plenty of sensors stop reporting below freezing.

In the catalog: 9
Work without a hub: 1 of 9
Hub required: 4
Most common radios: Bluetooth LE, Wi-Fi, Proprietary RF
Price range: $15 to $124

What decides compatibility

Check the operating range against the job. Freezer and outdoor use needs a sensor rated for it, and batteries rated for it too.
Most need a hub. Bluetooth models need something in range to relay.
Probe models put the sensing tip where the sensor body cannot go, which is how you monitor a fridge without the door pinching a radio.

How these connect to your system

A works-with badge does not say how the device gets there, and the path changes what you get. Direct means the maker built the integration and the device's own features tend to come with it. Via Matter means the standard controls work and anything unusual about the device may not carry over. Via a hub means you need a second box, usually the maker's own, before it works at all.