It has been nearly five years since Onvis first introduced the CS1, an integrated alarm and contact sensor that also included temperature and humidity sensors. Now, the company has fully adopted Thread (sometimes referred to with the prefix “Matter over”), and has released the successor to this device – the CS2 Security Sensor, which utilizes Thread instead of Bluetooth.

The physical design of the CS2 remains similar to its predecessor but now supports HomeKit over Thread, offering improved response times and extended battery life, operating on two AA batteries.

The CS2 functions both as a contact sensor and a system alarm, both of which are integrated with Apple Home. This ensures you have a fully operational contact sensor utilizing Thread, alongside an alarm with all four modes accessible within HomeKit – Off, Home, Away, Sleep. This flexibility is akin to other alarm systems from brands like Aqara, and also includes support for ‘Critical Alerts,’ an Apple Home feature that delivers important notifications regardless of whether your phone is in do-not-disturb mode or any other setting that usually blocks notifications.

The alarm itself is capable of producing an ear-piercing 120dB sound, which can be calibrated to three different volume levels and offers a variety of tones. Users can choose from fifteen distinct sounds for various alarm modes, including one for normal daily door opening. Additionally, the sound can be delayed when the door is opened, serving as a reminder to close the door if left open. This delay can also function as a countdown when setting the CS2 as an alarm, giving you sufficient time to exit the premises before the alarm is activated. Furthermore, the device includes temperature and humidity sensors, which are recognized as separate sensors by Apple Home.

For optimal performance of the CS2, a Thread Border Router is required, which is available in the HomePod Mini, 2nd gen HomePod, and certain models of the Apple TV4K.

The CS2 is currently available for purchase on Amazon.com for US$34.99. However, applying a 15% discount coupon reduces the price to just US$29.74.