Coil covers are to protect the coil in operation and should remain on the coil during use. It is a good idea to use a coil cover on any metal detector as the wear and tear of using a detector can cause damage to the bottom of the coil. This coil cover will protect the bottom of the coil from scratches and marks which may reduce the second hand value of the detector.

Note: it is far cheaper to replace a coil cover than it is to replace a coil.