Keeper? 18 in Marine Twin Anchor? bungee cords are made from the highest quality materials for long-lasting dependability no matter what the application. All Keeper? bungee cords are designed to withstand UV rays and weather damage with durable outer jackets. Premium rubber ensures top quality performance and outstanding toughness. Twin Anchor Marine Cords? are made with stainless steel double wire hooks with molded grip. Bulk.