OEM Sloan part. The inside cover sits on top of the diaphragm assembly just under the chrome plated outside cover at the top of the flush valve. It is designed to seal the upper valve chamber, preventing leaks and, potentially, over-long (or non-stop!) flushes. If you observe either of these, or a "chattering" noise when the toilet or urinal is flushed, you may need an inside cover.
This black version is used on most Sloan manual (handle flush) flushometers. There is a purple version as well, but it is very uncommon. For that, please call our parts department and specify Sloan Part No. 0301336 (A-71-1) and we will be happy to get it for you.
