I couldn’t tell from the website what it was measuring. Could it be a digital dynometer?
I just posted my own review of iThlete: https://www.sprint42.com — one thing I considered writing about was a comparison between using a dynometer to iThlete, but I never got around to it. I did, however, compare iThlete results with waking heart rate and a finger tap test (on iphone). iThlete seemed more consistent than either of these other tests.