OM3 is sufficient for short-distance applications, while OM4 delivers superior performance for long-distance transmission. They share identical appearance but differ by one grade in transmission speed and distance.

Both OM3 and OM4 are aqua-colored multimode fibers with the same appearance, compatible connectors, and mutually interoperable MPO cabling. OM4 features higher bandwidth and better attenuation resistance. It supports longer transmission distances at the same data rate and provides more stable 40G/100G high-speed links. For new computer room construction and cabling renovation, OM4 is the preferred choice; OM3 is fully adequate for existing legacy short-distance network points.

Both OM3 and OM4 used for MPO cabling are 50/125 μm laser-optimized multimode fibers, with an identical aqua-colored outer jacket. Their core differences lie in bandwidth, transmission distance and high-speed bearing capability:

OM3 features an effective modal bandwidth of 2000 MHz·km. It supports up to 300 meters for 10G, and approximately 100 meters for 40G/100G (SR4). It is suitable for small and medium-sized computer rooms, short-distance (<100 m) 40G backbone links, and budget-sensitive scenarios.

OM4 is an upgraded version of OM3, with a modal bandwidth reaching 4700 MHz·km (about 2.35 times that of OM3). It supports 10G transmission up to 550 meters, and 40G/100G (SR4) up to 150–300 meters. It is more ideal for large and medium-sized data centers, 100G backbone networks, long-distance high-density links and future network upgrades. OM3 and OM4 are fully interoperable, and OM4 is the preferred choice for all new cabling deployments.