Material: The air valve cap is made of high-quality, high-density plastic, sturdy and durable. Quick Inflation & Deflation: The air valve cap fits into a 20 mm (0.78 inch) hole and is compatible with Boston valves for faster inflation and deflation. Rubber Pad: The bottom of the air plug features a rubber gasket that helps prevent leaks and provides a secure seal. One-way inflation valve allows for quick inflation. Nice Design: The well-designed valve cap ensures leak-resistant performance with a two-way air valve system, making inflation easier and more efficient. Wide Compatibility: Fits most inflatable boats, rafts, rubber dinghies, and other inflatable products. Please measure your valve size before purchasing. Color: Black Material: Plastic Package Contents: 4 x Boston Valves 4 x Gaskets Note: Light and display differences may cause slight variations in color between the image and the actual item. Measurement error is +/- 1-3 cm.