The continuous filament bave is exuded by the silkworm to form its cocoon. It is composed of two brins which are stuck together with sericin or silk gum. The two brins are extruded from a pair of silk glands in the silkworm's head. The length of bave varies with the breed of silkworm, from 300 m to 1500 m. The thickness of the bave varies from 1.8 denier to 3.0 denier. See also brin.