Tracker – Wearable Basal Body Temperature (BBT) Monitoring Sensor and Fertility Charting App Includes Comfortable Armband (S/M – 8.5-15.5 Inch) ⭐⭐⭐⭐⭐ Description SizeA - Fertility Monitor (S/M – 8.5-15.5 Inch) ALL-IN-ONE OVULATION TRACKING ✔️ Tempdrop’s wearable sensor and charting app brings a full fertility charting solution to your smartphone. ✔️ Basal body temperature (BBT) is a major fertility indicator that allows women to understand their cycle. The Tempdrop sensor continuously monitors while you sleep, eliminating the need to wake up at the same time each day to catch a BBT reading. No more alarm clocks and no more hassle – sleep in! EASY TO USE ✔️ Wear the Tempdrop sensor on your upper arm during sleep and then sync whenever it's convenient. With an inexpensive, replaceable battery, there is no daily charging. Get manufacturer support and advice from a knowledgeable team 1-year manufacturer warranty and ongoing support! Thanks to our proprietary patented algorithms, Tempdrop will learn and pinpoint your nightly and monthly sleeping temperature patterns for the highest accuracy, helping you identify your fertility window and ovulation each cycle. Included Components: sensor, Armband, box, additional battery, battery removal tool, original pretty gift box! (THE ARMBAND'S SEAM SEPARATED IN ONE AREA AFTER WASHING IT SO I HAND SEWED IT AND REINFORCED IT. It in NO WAY affects the function, simply aesthetic!) The battery lasts so long!