Littelfuse Metal Oxide Varistors - LA / MA / ZA Series. Littelfuse metal oxide varistors are compact and versatile, and can be used within a wide range of applications. The LA series of MOV s are radial-lead varistors that are designed to be operated continuously across AC power lines. The MA series of MOV s are axial-lead varistors that are designed for use in a wide variety of board level industrial and commercial electronic equipment, protecting components and signal/data lines from low energy transients. The ZA series of MOV s are radial-lead varistors that are designed for use in the protection of low and medium-voltage circuits and systems. Typical applications include motor control, telecom, automotive systems, solenoid, and power supply circuits to protect circuit board components and maintain data integrity.