Price is for a single screw with a stainless washer and a neoprene washer
US Thread (1/4 20) Stainless Fin Screws with Washers
You would hate to miss a great day of windsurfing because you are missing a super small part like a screw! The fin screw that you use to hold the fin to the board it is a critical piece of equipment and they aren't expensive - you should have extras. These are stainless steel so they won't rust in salt water or get stuck in your fin. The threads are 1/4-20 (or US Style as opposed to metric) and they come in a variety of lengths. If you have a windsurfing board with a power box or tuttle box style fin box, these are the kind of screws you will need to hold the fin to the board. You can also check out the 6mm (metric) version if your fins require that.
These fin screws come with both a stainless steel washer and a neoprene washer (just like what your board came with from the factory!).