The WS9901 is a low-popularity serial flash memory manufactured by Winbond Electronics. Although it is not commonly used in electronic circuits, it is a reliable and high-quality component. The WS9901 is a balance in supply and demand status, making it readily available for manufacturers. However, the fake threat in the open market is high, so caution must be taken when purchasing this product. It is also halogen-free and complies with environmental regulations.