The 4.3” Thruster Fin Set is designed for maximum grip and feel while surfing. They come stock on the Phase Five Zeevo surf style boards. This tri-fin set includes a total of three 4.3” surf fins. Compatible with classic FCS fin boxes. Includes fin bag and FCS fin key.

https://www.phase5boards.com/blogs/phase-5-wakesurfers-blog/tips-how-to-install-surf-fins-with-john-akerman-drew-danielo