Function: 1. Easy control: wireless controller allows convenient and flexible remote control of crane, very useful. 2. Wide tool: Suitable for bridge cranes, upper cranes, chain cranes, monorail queues, concrete pump trucks and so on. 3. Sturdy Coating: The solid ABS coating is very comfortable to hold, which is also waterproof, insulating and durable. 4. Working instructions: use with contactor. You cannot connect directly to the power source as this will damage the motherboard. 5. Switch 2 pcs: including 2 pcs. Control switch with transparent panel, making operation much simpler. Specification: Item Type: pilot for crane; Product Material: ABS Product Model: YU-4S Temperature range: -5 - 85 ℃ Radio Frequency Point: 800 MHz Degree of protection: IP68 Control distance: Ok. 100 meters / 328,08 feet (in open environment) Adapter battery: 2 x AA 1,5 V battery (supplied without battery). List of packages: 2 x pilot for crane 1 x Transmitter 2 x Protective Cover 2 x fuse 1 x User Manual Note: Do not disassemble the product, as this may result in electric shock. Follow the instructions.