Dropper seatpost, 30.9 mm diameter. Perfect for gravel. It can be seen branded as Giant, as they manufacture for them. It came with my gravel bike and I removed it because I don't use it. Check the specifications on the website postmoderne.com.

As a technical detail, this model stands out because, in addition to its usual dropper function, it incorporates a small additional 30 mm suspension system to absorb bumps on the terrain.