M10 Adjustable Endlinks. Sold as a set of 2.

When the vehicle height is lowered by installing lowering springs or coilovers, the link rises above the standard angle, which degrades the vehicle's original performance and affects ride comfort. At this point, by using an adjustable stabilizer link to match the standard link angle, it allows the suspension to move smoothly regardless of the ride height.

In other words– it adjusts the length of the link according to the ride height to bring all functions close to the standard 'initial value (initial performance)'.