This 4-Channel DWDM Optical Passive Mux/Demux is engineered to maximize the capacity of existing fiber optic networks while minimizing the need for new fiber deployment. Operating with 100GHz channel spacing and supporting ITU channels C52-C55 (1525-1570nm range), this module enables the multiplexing or demultiplexing of four discrete wavelengths over a single-mode fiber. The unit includes both an Upgrade Port (UPG) and an Express Port (EXP) to ensure seamless scalability and future expansion. The UPG supports additional wavelengths within the 1525-1570nm range (excluding active channels), while the EXP accommodates O-band and L-band wavelengths (1260-1520nm and 1580-1620nm), providing a cost-effective path for network growth. Equipped with 40-inch, 900um fiber pigtails, this DWDM Mux/Demux is optimized for outside plant environments (OSP) and easily integrates into standard fiber optic splice enclosures.This 4-Channel DWDM Optical Passive Mux/Demux is engineered to maximize the capacity of existing fiber optic networks while minimizing the need for new fiber deployment. Operating with 100GHz channel spacing and supporting ITU channels C52-C55 (1525-1570nm range), this module enables the multiplexing or demultiplexing of four discrete wavelengths over a single-mode fiber. The unit includes both an Upgrade Port (UPG) and an Express Port (EXP) to ensure seamless scalability and future expansion. The UPG supports additional wavelengths within the 1525-1570nm range (excluding active channels), while the EXP accommodates O-band and L-band wavelengths (1260-1520nm and 1580-1620nm), providing a cost-effective path for network growth. Equipped with 40-inch, 900um fiber pigtails, this DWDM Mux/Demux is optimized for outside plant environments (OSP) and easily integrates into standard fiber optic splice enclosures.