RELIABLE AND ACCURATE: Measures Basal Body Temperature (BBT) to 1/100th of a degree precision (e.g. 97.41 F) in Fahrenheit or Celsius. Perfect for Trying to Conceive (TTC) Naturally.EASY TO USE: Simply place under tongue and close mouth for about 90 seconds; Soft Beeping Alarm indicates the completion of the measurement.LARGE BLUE SCREEN WITH BACKLIT: Easy to read in the dark. Recall 30 temperature records in memory.WATERPROOF AND FLEXIBLE TIP: Waterproof and Flexible thermometer tip for easy to use and clean.MONITOR YOUR OVULATION CYCLE with Premom: Use Premom app to do the charting and interpretation for you. Just log the temps in the premom app. It will identify your BBT spike, graph your temps, and create your coverline -- so you can identify your fertile window easily.