www.thedriller.com/articles/85735-utility-line-locator
Utility Line Locator
October 4, 2006

The RIGID SeekTech SR-20 utility line locator from Ridge Tool Co. uses a combination of multi-directional antennas, a mapping display and processing mechanism to provide users with information to locate underground utilities. Accompanied by audible signals, its mapping display shows target line direction and changes in direction; left-right guidance arrows; signal strength; and a proximity number that increases as distance to the target decreases.
Ridge Tool Co., Card No. 113