The ISO-trackerâ„¢ app allows the user to seamlessly connect to the Bluetooth device (iso-tracker.com) to see in real-time, their force output, the max force output reached, and the average force exerted during the session. Also, auditory feedback lets you know when youve reached your set target force, as well as when youve reached the target hold time/reps. (Change the mode with a tap of the Average button, to swap to Average+ to have the app count reps, instead of time.) The app will read in Lbs, as well as Kgs.