The GRIGRI, of the French brand Petzl, is probably the most popular assisted braking belay device in the world and over the years has become an icon of sport climbing. Its upgrades have very slight modifications since the original model back in 1991. Despite its high price compared to other belay devices, in Spain its use is widespread due to the false belief that it has an automatic braking system, making belay much easier. The truth is that it is described as a semi-automatic device and its use is only recommended for experienced climbers since feeding rope effectively is generally tricky and locking the brake for this task can be even dangerous.
Although the GRIGRI belay technique is very similar to the generic technique, it has some details that are described in depth in this video from Petzl.