The Canopy Mica is an OEM part for GE microwaves. This part covers the waveguide channel, preventing food particles and grease from entering the microwave's internal mechanisms.   Causes of a bad canopy mica can include exposure to high levels of moisture or grease, physical damage such as cracks or burns, and general wear and tear over time.   Symptoms of a bad canopy mica include: Sparks or arcing during microwave operation Burn marks or discoloration on the mica sheet Unusual noises while the microwave is running Uneven cooking or heating of food This OEM GE part is also compatible with Hotpoint, RCA, and some Kenmore models.WB06X10638 (AP3883317) replaces 1166457, AH1017735, EA1017735, PS1017735.