Compatible models: For 2, Air2, Air3 Drone, (consult customer service for other models). Control mode: Through the control of the fill light at the bottom of the drone, when the dropper senses that the fill light is turned on, the delivery be executed. Charging range: The charging interface adopts Type-C, the red light is always on when charging, and it automatically stop when it is fully , and the green light always be on, and the battery life be about 10 hours. Power display: The battery level is displayed through 4 blue LED lights, 1 is 25% left, 2 is 50%, 75% is bright, and 4 is 100%. Fixing method: Fastening by Nylon buckle binding. Applicable size: suitable for cylindrical objects with a diameter of 40-55mm. Precautions: This product is a drone expansion accessory, used for rescue, material delivery training demonstration, please abide by the law. Please keep it away from crowds when using, and it is forbidden for to use it. Since each user's usage and operation ability are different, our store is not responsible for safety accidents caused by the use process. Color: As Shown Material: Metal Package Contents: 1 x Double Thrower Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.