The EL817S1(B)(TU)-F with Optocouplers SMD-4 RoHS is a 4-channel surface mount optocoupler manufactured by Everlight. It features a pair of LED input channels light-activated insulated output, complete isolation between input and output, and a glow clamping output. The optocoupler is constructed using RoHS compliant materials and is available in a variety of package styles, making it suitable for a wide range of applications. the EL817S1(B)(TU)-F is used to reduce the affects of high voltage supply lines, interference, and signal levels, helping to keep sensitive electronics safe from damage.