Silicone circle design: The screws are equipped with black silicone rubber rings. The rubber O-ring helps reduce looseness during use, providing increased stability for surfboard screws and extending product lifespan. Durable material: The fin screws are made of high-quality stainless steel, resistant to rust, suitable for prolonged use in seawater without concern for damage. Easy installation: Installation is simple and requires no special tools. Screws can be tightened by hand in minutes, or easily secured using a Phillips screwdriver. Strong compatibility: Designed for surfboard center fin applications, compatible with longboards, SUPs, single fin setups, and paddleboards. Product package: Includes 4 sets of surfboard longboard fin screws (34mm) with a plastic storage box and a complimentary small drawstring bag. Ideal for everyday use with convenient spare availability. Please verify the required size before purchase.