The thickness of the cocoon shell is not constant and changes according to its three sections. The central constricted part of the cocoon is the thickest segment, while the dimensions of the expanded portions of the head are 80 to 90 percent of the central constricted . The weight of the silk shell is the most consequential factor as this measure forecasts raw silk yield. As with other characteristics introduced in this chapter, shell weight differs in correspondence to varieties of silkworms. Further, weight is also influenced by the type of technology used for rearing and mounting. In practice, uni and bivoltine species produce heavier shell weights than multivoltine species.