Varistor Products Line Voltage Operation, Radial Lead LA Varistor Series The LA Series of transient voltage surge suppressors are radial-lead varistors (MOVs) that are designed to be operated continuously across AC power lines. These UL recognized varistors require very little mounting space, and are offered in various standard lead form options. The LA Series varistors are available in four model sizes: 7mm, 10mm, 14mm and 20mm; and have a VM(AC)RMS voltage range from 130V to 1000V, and an ener.