Here is a breath monitoring wearable device that teaches you how to breathe properly while giving you real-time feedback. The Oxa smart shirt & bra come with guided exercises. They provide you with data on breathing rate and depth, heart rate variability and body temperature in real time.
Each shirt or bra comes with a sensor that connects to your iOS or Android device. Oxa is compatible with Strava, Google Fit, and Apple Health. The Oxa sensor lasts up to 24 hours on battery. It measures 1.5 x 1.5 x 0.5 inches.[where to get it] [official site]