White's GMT

The GMT was White's serious nugget machine: 48 kHz, automatic ground tracking, and an iron identification system that let you leave most of the hot rocks and boot tacks in the ground. Prospectors ran them in the worst ground the western states could offer and kept finding gold with them, which is the only recommendation that counts. The technology did not disappear when White's did, since the same gold platform continues in the Garrett Goldmaster 24K. GMT coils, covers, switches and parts are here.