The SMAJ18A is a TVS (transient voltage suppression) diode with an SMA RoHS (Lead-free RoHS compliant) package from the manufacturer Yenji. It is designed to provide protection for sensitive electronics and circuitry from voltage spikes up to 18V. It has a breakdown voltage of 17V and a peak pulse current of 11.3A. The diode is built with an ESD (electrostatic discharge) protection protocol that provides more robust protection against ESD strikes. It is a two-terminal, bidirectional device and can be used in applications such as telecommunication systems, network devices, and automotive equipment.