The present paper presents the development effort and precommercial deployment of Explorer II - a semi-autonomous, self-powered, tetherless robotic platform, carrying a Remote Field Eddy Current (RFEC) sensor, for the inspection of unpiggable natural gas transmission and distribution pipelines in the 6 to 8 inch (152 to 203 mm) range, including those that feature multiple diameters, short radius and mitered bends, and tees. The system is based on a modular design that allows the system to be deployed in various configurations to carry out visual inspection and/or non-destructive evaluation (NDE) of a pipeline. The heart of this system is a RFEC sensor able to measure the pipeline's wall thickness. In addition, two fisheye cameras at each end of the robot provide high quality visual inspection capabilities for locating joints, tee-offs, and other pipeline features. The system can operate, including launching and retrieval, in live pipelines with pressures up to 750 psig (50 bars). The system is currently being offered for precommercial deployments and is expected to be commercially available in the Fall of 2010.