The advanced design of the F-90M Metal Locator contains a re-set function for storing and comparing measurements eliminating the need for adjustment of sensitivity. The F-90M includes a waterproof search antenna that can locate metal objects under more than a foot of water. Frequency : 9.7 KHz Waterproof antenna disk :  27cm Detectable Depth : 40cm (15 3/4") for a steel disc 10cm (3.9") dia. 60cm (23 1/2") for a steel disc 18cm (7") dia