Natural Cycles, the company behind a controversial FDA-cleared birth control app, is replacing its thermometer with a wristband that measures skin temperature, heart rate, and movement during sleep. The newly-launched wristband costs $129.99 and syncs with the Natural Cycles app, which uses an algorithm to determine a person’s “daily fertility status.”

Users can already track their fertility by pairing an Apple Watch or Oura Ring with Natural Cycles, but the wristband could be an option for users who don’t have either of these devices handy. While Natural Cycles also works with newer Samsung Galaxy smartwatches and the Galaxy Ring, it’s meant for temperature-based period and cycle tracking when used with these devices — not as a way to prevent or plan pregnancy.

Natural Cycles initially offered a basal thermometer with its annual plan (or available separately for $14.50) so users could take their temperatures manually. Natural Cycles spokesperson Lauren Hanafin tells The Verge that users can continue using the thermometer if they currently have one. The FDA later gave Natural Cycles approval to collect data from third-party devices, like the Apple Watch and the Oura Ring. Hanafin says the company received authorization from the FDA to start using other temperature-tracking wearables without requiring additional approval, allowing it to launch the new wristband.

Privacy concerns related to period-tracking apps grew following the Supreme Court’s decision to overturn Roe v. Wade, but the Electronic Frontier Foundation notes that while users should review the security and privacy protections of the app they choose, they aren’t an “immediate threat” to abortion-seekers. Natural Cycles says it uses pseudonymization and encryption to conceal your information, while its band only collects data that’s “necessary.”

Natural Cycles first introduced its wristband to “select” people as part of the launch of its perimenopause feature in October. The band supports Bluetooth 5.0 LE, and offers a battery life of up to 14 nights after it’s fully charged via USB-C.

The Natural Cycles Band is available for purchase for $129.99, and is also included with the company’s annual plan for $149.99. Users who already have a Natural Cycles subscription can upgrade to the band for $99.99 for a limited time.