Garrett 8" PROformance Mono search coil for Mark II Detector should be used for maximum detection response in areas with light to heavy mineralization. PROformance coils feature heavy-duty, seamless epoxy-filled technology for the ultimate in weather and water-proofing. Each search coil also sports an open design, which provides easier movement through water and near-neutral buoyancy as well as excellent visibility of the ground beneath the coil - an invaluable feature when pinpointing!