The NEW iP501-300 RS232 Optical Probes are designed for reading and programming ANSI and IEC electrical power meters. NOW, THERE IS NO NEED TO CARRY 2 OPTICAL PROBES FOR READING OR PROGRAMMING METERS THAT EMPLOY EITHER TYPE OF OPTICAL PORTS. In addition, they incorporate a new smaller housing design that make them even lighter weight but still rugged with their Polycarbonate Glass Fiber Reinforcement material.