Silicone circle design: The screws are equipped with black silicone rubber rings. The rubber O-ring helps reduce looseness during surfing, making the surfboard screws more stable and increasing the product's service life. Durable material: The fin screw is made of high-quality stainless steel, which is resistant to rust. Suitable for prolonged use in seawater without damage. Easy installation: Installation is simple and does not require additional tools. Can be tightened by hand in minutes, or easily secured with a Phillips screwdriver. Strong compatibility: Designed for surfboard center fin applications, compatible with longboard, SUP, single fin, and paddleboard models. Product package: Includes 4 sets of surfboard longboard fin screws (34mm) with a plastic storage box and a complimentary small drawstring bag. Sufficient for daily use and convenient for spare replacements. Please verify the required size before purchase.