This year marks the first time that goal-line technology (GLT) will be used at The Union of European Football Associations (UEFA) Euro tournament. UEFA approved GLT for the tournament earlier this year, and selected Hawk-Eye Innovations as the provider.

Incidents in past tournaments have prompted the inclusion of this technology at higher levels of soccer. At Euro 2012, the Ukrainian team was denied a goal after an English defender kicked it out of the net. Coaches and players argued that the ball had crossed the goal-line, however the initial call stood. The loss led to the elimination of the Ukrainian team from the tournament.

Hawk-Eye’s technology uses seven cameras per goal (14 total) placed throughout the stadium to track the location of the ball on the field. The cameras are able to find the ball even if only a small part of it is visible. As soon as the ball crosses either goal line, a notification is sent to a wearable device on the referee’s wrist. Hawk-Eye claims that the system is accurate enough that a goal can be triggered even if the ball can only be found by two of the seven cameras.

It also claims that the system is reliable enough (to the millimeter) that no broadcast replay would be able to disprove a call. All 10 of the French stadiums that games will take place in will be equipped with the technology.

Euro 2016 is happening right now in stadiums across France, with the final taking place on July 10. See below for an in-depth look at how GLT is tested for accuracy.