It’s called DigitalLink. It comes with my ProChrono DLX chronograph. It connects to the chronograph Bluetooth, from my phone and records each shot. It’s a free App Store download, and there is a computer app to that you can sync too. It’s even easier than it sounds. The whole thing only cost me a little over $100, chrony and all. I tested the accuracy alongside a LabRadar, and it was nearly identical.What app are you using to track this?