The data checker communicates via a high frequency element. All units are small and stable with a powerful anti-interference feature.Because they are packed with high-precision SMD. This ensures the reliability of the product. They can be widely used for systems that require wireless control. Power Source of Controller:2 x 1.5V AA/AAA Batteries. This item is in the category "Business & Industrial\Material Handling\Hoists, Winches & Rigging\Lifting Machine Parts, Rigging\Lifting Machine Remotes". The seller is "topeyseller_best" and is located in this country: CN. This item can be shipped worldwide.