Holds pressure up to 2.5 PSI. This valve is intended to be used without the cap. The included fine-mesh screen will help keep debris out of the valve. If your valve should start leaking while boating, use the Pressure Relief Valve Cap (Item # 38534.01, sold separately) as a back up to keep the floor airtight. To clean the valve, follow the directions given in the video linked here on this page.