Premium Material: Made of 316 stainless steel, solid and stable. Anti rust in fresh or salt water, greater strength and corrision resistance performance than regular stianless steel or zinc plated fasteners. Extra O Rings: 3 pack screws M5 come with extra 3 O rings. 6 pack screws include extra 6 O rings. O ring provide strong sealing and good airtightness, prevents leaking. Easy to install: This tool less stainless steel screw and plate for all standard center fins can be tightened easily with your fingers. Perfect replacement part. Widely Compatible: The screw is compatible with most brands and boards. Fits all universal (US) fin boxes for surfboard longboard, SUP, single fin, paddleboard. Excellent replacement fin box screws. Abahub Warranty: We've been manufacturing fins for over 10 years. We know what we're doing and we stand by our products. If you're not happy with our products, we'll offer you replacement or refund with "No Question Asked" warranty. Abahub Paddle Board Fin Screws 6 Pack - 316 Stainless Steel Replacement Fins Box Screw and Plate with Six Extra O Rings for SUP Inflatable Stand Up Paddleboard Surfboard Longboard