Patent ID: 8758471

Claim:
A mat comprising: a first main face; a second main face opposite to the first main face; at least three layers comprising: a first layer occupying a first area from the first main face along a thickness direction of the mat, the first layer comprising a first long fibrous substance which comprises an inorganic fibrous substance; a second layer adjacent to the first layer, the second layer comprising a short fibrous substance which comprises an inorganic fibrous substance and which has an average fiber length shorter than an average fiber length of the first long fibrous substance; and a third layer occupying a third area from the second main face along the thickness direction of the mat, the third layer comprising a second long fibrous substance which comprises an inorganic fibrous substance and which has an average fiber length longer than the average fiber length of the short fibrous substance; and an intertwined portion extending from the first main face to the second main face, the intertwined portion comprising the first long fibrous substance, the short fibrous substance, and the second long fibrous substance which are more closely intertwined with each other than the inorganic fibrous substances in a portion except the intertwined portion.