Feature: 1. There are four gears of A gear(200Hz), B gear(800Hz), C gear(1200Hz) and D gear(probe tube), which can be adjusted to meet different conditions. 2. Composition of a metal receiver and high‑quality earphones, imported components, high sensitivity, clear sound quality, and super detection ability. 3. The built‑in FM wireless transmitter component can wirelessly transmit the signal to a long distance. 4. Equipped with expansion jacks, which can be connected to external devices for additional functions. 5. Built‑in lithium battery, with unique FM transmitting function, easy to be manipulated and carried. Specification: Item Type: Pipe Leak Detector Material: MetalCurrent Consumption: 10MA Battery: 3.7V Rechargeable Lithium Battery (Delivered with Battery Included) Four Audio Options: A Gear (200Hz), B Gear (800Hz), C Gear (1200Hz), D Gear (Probe Tube) Probe Sensitivity: -70Db The Highest Audio Magnification: 20000 Times Penetration: Cement Pipe, Steel Pipe, Iron Pipe Voltage: 100-240VHow to Use: Insert the earplug into the earphone hole, insert the probe into the MIC hole, turn the volume/switch button clockwise, the power indicator light will light up, adjust the gear knob ABC three gears, select the best effect. F-999B has another FM transmitting function. This function is automatically turned on after the antenna is inserted into the FM jack. The transmitting frequency: about 100 megabytes.. Package List: 1 x Probe Host 1 x Earphone1 x Power Adapter1 x Probe 1 x Probe Needle 1 x Manual 1 x Connecting Wire