The Proton 4 is the ultimate detector for iron and steel targets. It has a one gamma sensitivity, which is the maximum practical sensitivity for a towed magnetometer. It's maximum range capability of 1500 feet on each side (3000 foot total swath) lets you search a wide area quickly and completely. The mag is also a good choice to locate a variety of smaller targets such as pipelines, anchors, chains, cannons, dredge heads, etc. It is especially useful when objects are buried in the bottom and can't be found with sonar or video search systems. The detection range is unaffected by the medium between the magnetometer and the metal target. Performance does not change whether detecting through air, water, silt, sand, or solid coral. It's extremely large detection area make this magnetometer the ideal choice for both commercial operations and professional wreck hunters. The Proton 4 is in use by military units, law enforcement agencies, and commercial diving companies world wide.