DD coil is preferred where the most severe mineral conditions exist. Garrett exclusive sliding mount design provides the advantages of a center-mounted coil (balance, easy tilting). Solid coil design is more resistant to impact. Front half of solid coil’s top surface provides a large, flat surface to spread a handful of dirt to sift for a tiny nugget. Ideal coil for prospectors and relic hunters for improved gliding/scrubbing over brush, rocks, etc.