JOINWIT JW3109 is an optical power meter that provides up to four output wavelengths measuring: 650 nm red source, 1310/1550 nm wavelengths for single-mode fiber, or 850/1300 nm wavelengths for multimode fiber. Wide range of power measurement: from 650 nm to 1550 nm. High stability of the output. Optical power meters for fiber optic networks: For the installation, maintenance, and testing of single-mode and multi-mode networks and cables.