“Filling material” means cotton, wool, kapok, feathers, downs, hair, liquid, or any other material, substance, or any combination thereof, loose or in batting, pads, or any other prefabricated form, concealed or not concealed to be used or that could be used in articles of bedding or upholstered furniture.
Source:
Section 19007.5, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=BPC§ionNum=19007.5..