This is a key component used to connect devices with different interface types in single-mode fiber networks. One end of it features a small, high-density LC connector, while the other end has a standard size SC connector, and it comes in two different polishing styles (UPC and APC). Its primary function is to achieve physical interface conversion between devices and efficient, low-loss signal transmission. It is commonly used in scenarios such as fiber to the home (FTTH) and optical line terminal (OLT) access.