The 3300 Series meter relays offer a wide variety of applications in control, alarm, and limit use. Photo conductor sensing eliminates all interference with the indicating meter. These relays incorporate an amplifier input that drives a rugged high-torque pivot and jewel meter. Metal-cased "Rugged Seal" construction withstands rigorous environmental conditions. The metal cover with a drawn steel plated rear case gives complete magnetic isolation for steel panel mounting. In addition, each meter is moisture, dust, and dirt proof for use in wash-down areas. Fail-safe circuitry opens output relays in the event of power failure. Two different sizes, 3-1/2" and 4-1/2", are available in both single and dual set point models.High-gain transistor switch circuitry provides accurate switching with a “dead band” of no more than 0.5% of full scale (F.S.). All AC current units offer ±3% of accuracy F.S. This style meter is ideal for many other electrical functions.