3/8″ ISO A Quick connector Rubber caps hydraulic quick coupling caps help, preventing dust.SpecificationColor: Yellow, red, blue, blackMaterial: RubberPacking List: 1 Set Quick Connector Protective CapAdvantageConnector covers: selected material: made of stable plastic material, tear-resistant design, built to last.InstructionThe selected material is made of stable rubber material with a tear-resistant design built to last.NotePlease note the diameter of the dust cap and plug, After installation, please check whether it is stable to prevent it from falling.