The Minelab 17 inch Smart Coil is the first of the FBS2 smart coils to the public for the CtX 3030........ Application The waterproof 17 × 13-inch elliptical Double-D coil provides maximum depth for specialised treasure hunting. It is also great for wide ground coverage in open spaces. A protective skidplate is included. Water Protection Waterproof: Submersible to 3 meters. Ideal for wading at the beach, or detecting in streams.