Tanned, dried, scraped pig skin. While a decent leather, it neither protects nor insulates particularly well.
The following animals provide pigskin.
Pigskin is one of the least protective textiles in the game, at tied 21st most protective, or tied 8th least protective. It has terrible insulation, being the 4th and 3rd worst for heat and cold respectively. It also has a fairly low beauty factor and market value. Thus it should only be when there is no alternative or where its stats have little effect on the utility of the resulting item, such as in clothing production quests or Armchairs whose beauty rarely significantly affects a room's quality.