The leashes are made of bungee cord with a velcro strap on the rod end and a small carabiner on the other to attach to the deck. I buy those on ebay and swap out the carabiner with one also bought on ebay that have a locking screw barrel on the opening for extra safety. They are great and saved me from loosing a $600 set up once. While fighting a 30+lb Yellow I was shifting position on the seat and got a little too relaxed and it took of to the left side and pulled the rod right out of my hand. I looked at the rod going into the ocean with a shocked stare and in a second when I realized what had happened, I grabbed the leash pulled the rod back to me from the ocean and proceeded to land the large Yellow. I use them the whole time I'm in the water, not just coming in through the surf. Here is a link I saved from the last purchase.
https://www.ebay.com/itm/5-Kayaking-...d/281423212078