These Hose Replacement O-Ring includes 10 O-Rings. Use to replace worn O-Rings in your Game Ready® product. For GRPro 2.1 only. The O-rings that are part of the Game Ready Hoses. Eventually the rubber O-rings used at all the hose connections will need to be replaced. Over time, as rubber does, the O-rings may swell, crack, rot, harden or otherwise degrade.  A problem will be noticed when the unit starts having issues with leakage, difficulty in plugging in a hose, certain error codes appear, etc. If hardening is the issue, a little silicone spray (available separately) to lubricate might solve the problem.