An optical module provides optical-electrical conversion ports, enabling optical transmission between an RRU and other devices. It also explains how to replace the RRU and optical modules. This chapter describes the procedures and precautions for replacing a common RRU, replacing a blade RRU, and replacing a non-blade RRU with a blade RRU by reusing mounting kits. You are advised to. RRU is short for remote radio unit. The exteriors of components and cables in this document are for reference only. Characteristics: Feeders are designed with insulation and shielding to protect against environmental factors.