Depends on which one your talking about but...Sid Wilson's first mask was a Canadian C3 Gas Mask and seven other models of gas masks. The C3 was used for the self titled album cover. The next mask he used for Iowa had the same face, except that there are teeth in the mouth area. It is also a full head mask that resembled a skull. For Vol. 3: (The Subliminal Verses), Wilson's mask dropped away from the gas mask face motif. It now looked like an actual skull, with two or three crooked teeth. Halfway through the tour, however, he changed the mask to a full-head skull, as he had shaved his hair off. Wilson's mask for the latest album All Hope Is Gone is known to have its eyebrows and mouth move in a mechanical fashion and also has antennae at the top of the mask which can also move. It is rumored that the mask is made to resemble Starscream, his DJ namesake. The electronic glass eyes on his mask are also known to light up different colors, most notably red as seen during the music video for "Psychosocial".