Rolling swivel with double eyelet Round / Diamond. In fact, this swivel has a "Round" (round) and a "Diamond" (rhomboidal) eyelet which is used a lot when you need to use the silicone tube on one of the 2 sides. In fact, the rhomboid eyelet is very suitable for making the silicone tube rise better. The round eyelet, on the other hand, is better suited for quick couplings.