All power comes directly from the 4 to 20 mA input signal—no additional AC power source is required! Explosion-proof models provide safe use in hazardous locations and are easy to install and calibrate. These rugged, yet economical meters are ideal for use in hostile environments. Choose the backlit display option when mounting the meters in poor lighting conditions. Meters and backlighting option are powered directly from the 4 to 20 mA loop; no need for an AC power source, batteries, or additional wiring. Models with explosion-proof enclosures meet specifications for use in Class I, groups B, C, D and Class II, for Groups E, F, and G locations.