A marine grade linch pin is a type of fastener used to securely connect and lock two parts together. It is specifically designed for use in marine and coastal environments, and is made from corrosion-resistant materials such as stainless steel. This ensures that it can withstand the harsh saltwater and humidity conditions commonly found in these areas. The linch pin is easy to use, it can be inserted and removed by hand and it's commonly used in marine and boating applications, such as securing boat covers, tarps, and other equipment on boats and ships.