The Semi-Recessed Valve Cap & Collar functions with the Semi-Recessed Valve Body, p/n's Z60053 & Z60217. The cap is what makes the valve fully airtight.
The cap’s o-ring must be in good condition in order to maintain a proper seal for the inflatable’s air chamber.
The Cap with Collar includes a new o-ring.
Make sure to tighten the cap well to keep the tubes fully inflated when on the water.