The HeartMath sensor is the company's first mobile device after years of working only on computers.

WSJ: Review of Tink�� and HeartMath Inner Balance Sensor for iOS

The first time you use HeartMath, helpful slides walk you through how the product works.

WSJ: Review of Tink�� and HeartMath Inner Balance Sensor for iOS

HeartMath's proprietary technology is at the heart of GPS for the Soul, which was developed in partnership with HeartMath and bLife.

ENGADGET: HeartMath unveils Inner Balance iOS app and sensor for managing stress, clearing the mind

It measures what HeartMath calls coherence an algorithm applied to heart-rate variability, which the company says can reflect emotional states and stress levels.

WSJ: Review of Tink�� and HeartMath Inner Balance Sensor for iOS

If you're curious about your heart-rate variability and the other data that can be gleaned from it, I'd recommend the HeartMath Inner Balance for a comprehensive approach.

WSJ: Review of Tink�� and HeartMath Inner Balance Sensor for iOS

Over two decades of HeartMath research sets the foundation for this truly unique and effective approach to replacing old frazzled stress responses with a new level of personal balance and a deeper sense of ease and flow in the face of challenges.

ENGADGET: HeartMath unveils Inner Balance iOS app and sensor for managing stress, clearing the mind