Sloan OEM Part. Inside cover on Sloan flushometers. Sits just inside outer (metal) cover and over valve diaphragm assembly. Compatible with manual Royal and Regal flushometers. Also compatible with Regal SMO & DFSM/SFSM flushometers and those that have been retrofitted with "side-mount" sensors.
aka: 0301121, 0301278
