Fibrain FLTS-750 is a portable measurement system for attenuation measurements in fiber links by the transmission method, which is a preferred method for attenuation measurements by the PN/IEC ISO 14763-3 and PN-EN 61280-4-2 standards. The FLTS-750 integrates in one practical case a stable single-mode 1310/1550 nm light source and a power meter calibrated for six wavelengths (single-mode 1310/1490/1550/1625 nm and multi-mode 850/1300 nm). An automatic detection of the received wavelength makes bidirectional attenuation measurements in both transmission windows very fast and convenient. A large area of the detector guarantees stable and repeatable measurements, regardless of connector type (UPC or APC). A large, illuminated display ensures a perfect visibility under any conditions. Built-in rechargeable batteries lower the exploitation costs and guarantee a long time of field works. Large memory capacity and a USB communication port allow data archiving and processing.