How to mount your SUP fin to the US fin box

New to surf fins? Mounting a SUP fin for the first time can be tricky — this guide walks you through it step by step.
This applies to fins that use a US fin box.

How to mount the SUP fin
The fin has a bolt through the front base, with a small square nut (about 1×1 cm) on the other end.
1. Remove the square nut (keep track of the bolt — you will need it again).
2. Drop the nut into the fin box slot on the bottom rear of your SUP and slide it forward about 5–10 cm with the bolt.
3. On the fin, opposite the bolt, you will see a transverse slot (peg). Hold the fin at an angle, line up the slot with the fin box and slide the fin toward the tail.
4. Slide the fin forward until the bolt hole lines up with the square nut. Hand-tighten the bolt.
5. Before fully tightening, you can slide the fin forward or back. Further forward = more directional stability. Further back = easier turning.