Mansfield Genuine 630-0030 Flush Valve Seal The Red Seal Is The Only Seal To Fit The Tower Flush Valve. This seal is flat. After being used it may develop a ridge or cone shape. It is the most common cause of the toilet leaking and being hard to flush. The package says it's for 210 and 211 it is referring to the flush valve model number not the tank number. When installed you should be able to pinch the seal and spin it.