Fin screws for your windsurf board with either a Power Box or Tuttle box.
6mm / M6 thread is the most common for windsurf boards. (Some older fins, especially Tuttle box may use 1/4"-20 bolt threads,)
Stainless steel to prevent corrosion.
Power Box - 50mm is by far the most common length. 45mm and 55mm are the other possibilities. Rarely is it a different length.
Tuttle Box - Screw lengths can vary greatly in length. 30mm is a common length for boards with recessed cavities for the bolts to sit in. But there are also Tuttle Box boards that can use up to 100mm lengths.
Screw / Bolt only. Washers sold separately.
Click on the dropdown for length options.