Aqara Spatial Multi-Sensor FP400USB-powered multi-zone radar presence sensorWorth its $79.99 US price in an open-plan room where one sensor needs to distinguish a sofa, desk and doorway.Thread$79.99Needs a Thread border router
Sensereo MS-1 Interlink Smoke AlarmEuropean smoke alarm with linked sirens over ThreadMS-1 Interlink is the Sensereo smoke alarm I would choose for several rooms: its $10 premium over the ordinary MS-1 buys automatic linked sirens.Thread$59.99Needs a Thread border router
Aqara Multi-State Sensor P100One-piece hinged-door sensor with optional object monitoringP100 earns its place when fitting a separate magnet would be awkward on a hinged door or window.ThreadFrom $29.99Needs a Thread border router
ThirdReality Smart Water Leak Kit KM1Matter Wi-Fi water leak detector kitKM1 is useful when you want three leak locations feeding one alarm that can sit somewhere audible.Wi-Fi$39.99No brand hub or Thread router required
Heiman C1-M Carbon Monoxide AlarmCompact battery-powered CO alarm for North American homesC1-M is a reasonable CO upgrade for an existing Thread home when its small body and connected alerts matter to you.ThreadNeeds a Thread border router
Heiman L1-M Water Leak SensorCompact indoor water-leak sensor with an IP67 enclosureL1-M is a reasonable compact leak sensor for an existing Home Assistant installation, particularly where its IP67 enclosure matters.Thread€26.99Needs a Thread border router
IKEA ALPSTUGA Air Quality SensorMatter-over-Thread Air Quality SensorALPSTUGA is an appealing room monitor for the price, combining CO₂, particle, temperature and humidity readings with a display that works on its own.Thread$34.99Needs a Thread border router
IKEA KLIPPBOK Water Leak SensorMatter-over-Thread Water Leak SensorKLIPPBOK is a useful inexpensive local water alarm for a sink cabinet or appliance area.Thread$11.99Needs a Thread border router
IKEA MYGGBETT Door/Window SensorMatter-over-Thread Contact SensorMYGGBETT is a sensible low-cost choice for a closet light or indoor door check.Thread$11.99Needs a Thread border router
IKEA MYGGSPRAY Motion SensorMatter-over-Thread Motion SensorMYGGSPRAY is an attractive inexpensive trigger for hallway or closet lights, especially with directly paired IKEA lighting.Thread$11.99Needs a Thread border router
IKEA TIMMERFLOTTE Temperature/Humidity SensorMatter-over-Thread Temperature and Humidity SensorTIMMERFLOTTE is an appealing inexpensive room thermometer with useful smart-home potential.Thread$11.99Needs a Thread border router
Shelly Flood S Gen4Compact water-leak sensor with a built-in alarmShelly Flood S Gen4 is a sensible €18.90 buy for one sink cabinet, appliance tray or other spot where water is likely to collect.Wi-Fi€18.90No brand hub or Thread router required