It contains a transmitter and a receiver, which help the detector retrieve and interpret information about a detected target. Searchcoils are available in several shapes and sizes to meet a variety of hunting needs. Generally speaking, small searchcoils are designed to detect small shallow objects, while large searchcoils are used to find large, deeply buried objects. Coils can range in size from four to 12 inches in diameter. An all-purpose detector is usually equipped with an eight- or nine-inch searchcoil, practical for scanning parks, playgrounds, beaches and other popular coin-hunting locations.