Typically, single mode SFP modules are labeled as "SM" or "single mode," while multimode modules may be labeled as "MM" or "multimode. To determine if your SFP (Small Form-factor Pluggable) module is single mode or multimode, you can look for specific markings or labels on the module itself. The distinction is important as it affects network performance, distance, and overall cost. This means you can find combinations such as single-mode single-fiber modules or multi-mode dual-fiber modules: Most single-fiber modules are single-mode due to the complexity and cost of wavelength multiplexing in. Distinguishing between single-mode and multimode fiber optic cables can be done by considering several factors. Here are some methods you can use: Single-mode (SM): Typically has a smaller core diameter, usually around 9 microns.