Both the face mask and the earmuffs (used to make the masked earmuffs) are used to make the slayer helmet individually. However the masked earmuffs as an item cannot be used to make it. They must be disassembled into the respective items before a slayer helmet can be constructed.
When a player changes himself to female and switches to certain type of long hair while wearing a slayer mask, the character's head will become warped when doing emotes or other activities. This has since been fixed.