Don't get stuck on shore with missing screws! Stock up on M6 Stainless Steel Pan Head Phillips Screw.
The shorter screws are commonly used for kite and wakeboard fins, and foils. The longer screws are commonly used for windsurf fins.
To determine length you require, measure the entire length of the threaded portion (ie excluding the head). Or check with the product manual to determine correct length.
Standard drive is Phillips (#4).
Note: we also have M6 screws and M8 screws in Flat Head version (see link below). These are common for kite fins and foils.