You know it's a TableHockeyPro ProPuck by its distinctive ring.

We've all been looking for black pucks, but no one had any available; at least not in large quantities. Now you can get Stiga Style black pucks at a great price. These pucks are the same size and weight of the black pucks. One great feature is that our ProPucks are more resilient than the original Stiga black pucks. You know how the Stiga pucks get chipped up on the edges after several games, our ProPucks are much more durable and don't chip as easily.

Can you tell which is the Stiga puck?