MRAM comes in many flavors, but Everspin uses Spin-Torque (ST-MRAM) technology. MRAM stores data magnetically, which is in stark contrast to electron-based data storage techniques. MRAM retains all stored data when the device loses power (which means it is a persistent non-volatile storage medium). A perpendicular magnetic tunnel junction (pMJT), which HDD vendors use in read heads, serves as the memory cell. It uses standard CMOS transistors. The design consists of two ferromagnetic plates with an insulating dielectric layer between them. One plate is set to a known polarity (fixed layer), and the other plate's polarity can be changed (free layer). If both plates have matching polarity, the cell will be in a low-resistance state (1), and if they have different polarity, the cell will be in a high-resistance state (0). The device measures the resulting electrical resistance to determine if the cell holds a "1" or "0." The cell does not have to be erased before it is rewritten, which simplifies management and increases performance.