The Harrick Scientific Fiber Mate 2 fits in any Thermo FTIR (except the IS5 and Summit). Unit is designed to couple the Near and Mid Infrared light into a fiber for remote sample analysis. Low OH (glass) optical fibers are often used with the Fiber Mate 2 in the Near Infrared region (700-2500 nm) due to their low cost and durability. As shown (see photo) the Fiber Mate 2 has a source connection (right side) and return (left side going to the detector). Most applications use an off the shelf probe or bifurcated fiber for the source and return with standard SMA 905 connectors.