The 3M™ EMS extended range ball markers have a self-leveling design providing accurate, horizontal position regardless of how it is placed in the ground, making the job of precisely locating underground facilities easier. The 3M™ marker balls allow for the easy marking of telephone lines buried at a distance of 5 ft (1.5 m). Marker balls have a unique self-leveling feature, that insures the marker is always oriented to the surface, allowing for an accurate location. Passive marker balls provide accurate identification of buried telephone lines, helping to reduce the risk of accidentally excavating other buried facilities. All markers function without the need for an external power source. Their water-resistant polyethylene shells are impervious to minerals, chemicals and the temperature extremes normally found underground. An iD version is available which allows for the storage of customer specific information about the underground asset.