and high quality.Tightening the rubber O-ring by hand means that there will never be tools. This thumb screw is easy to install and requires no other tools. It is suitable for friendly beginners and surfers.These tool-free thumb screws are made of high-quality stainless steel, which is and stable, not easy to break, deform and fade, and will not rust in water or salt water. The O-ring acts as a "spring", ensuring that the screw is under pressure and can be tightened without scratching the circuit board.Suitable for all standard fin boxes, for long boards, super, single fins and paddle boards. Incompatible: The and paddle board owners reported that these are too short for those boards.The thread length is 16mm /0.63 inch, the length is 31mm/1.22 inch, and the plate size is 14mm /0.55 inch. This kit comes with 16 fin screws and plates.Material: Stainless steelcolour: silverPackage Contents:16 x Fins screwOnly the above package content, other are not included.Note: Light reflection and different displays may cause the color of the item in the a little different from the real thing. The measurement allowed error is +/- 1-3cm.