Specifications : Caps inner diameter: approx. 0.8 cm/ 0.31 inch Caps height : approx. 1.2 cm/ 0.47 inch Material : 100% zinc alloy How to maintain the valve caps To avoid the valve caps' natural oxidation and corrosion, we should maintain the valve caps with the following methods. 1, Avoid long time exposure of the valve caps to water or snow. 2, To unscrew and clean the valve caps, and to check the tire pressure on a regular basis, say 2-4 weeks/once, so as to prevent the oxidation of the valve cap threads and ensure the tire pressure normal. Package List : 4pcs pack,