The Gitzo short spike & rubber foot reliably support tripods on softer terrain, like grass or mud. The rubber foot is attached to the short spike like a cap, and can be pulled off when it’s time to use the spike. The resistant rubber material is highly stable, even on slippery floors. The diameter of the widest part of the rubber foot is 30mm. The spike is made of high-quality machined steel. This foot is compatible with all Gitzo tripods with 3/8” threaded legs. The GSF30S replaces the G1220.129B3.