ERS SIDE FIN KIT - 2 BLUE FLEX + 2 BLACK HARD FINSGreat for hold and stability. A SUP staple that gives you excellent grip and tracking assistance in any type of water. 2 Flexible Blue fins and 2 Rigid Black Fins. Does not include grub screws. Compatible with Earth River SUP 2019 and later Skylake, GT, V3, DUAL, and DECK boards only Not suitable for Hala NRS Red Paddle Co Starboard boards.