Headset, Application Monitors the Received Signal in High Noise Level Areas After Being Plugged into Locator's Receiver Jack, Cable Length 45 in, Color Black, Silver, Features Adjustable, Cushioned Earpads, Provides Audible Signal Strength for Accurate Identification, For Use With Tempo 501 (Grainger SKU 1UG78) and 521A (Grainger SKU 34E853) Locators, Operating Frequency 447.5 kHz, Outside Diameter 53 in, Product Type Headset for Greenlee Tracker II