Worn indoors about twice and stored in a warehouse. The included battery also works without any problems. This is a cooling water-cooling vest that circulates cold water to cool the body. It's easy to use in 3 steps: ① Pour about 500ml of cold water into the tank on the back. ② Put a frozen ice pack (frozen plastic bottle, ice, or ice pack can also be used) into the tank. ③ Connect the battery and turn on the power switch. The cooling system cools by circulating cold water with a cooling unit built into the vest. It feels comfortable to wear and cools the upper body. The lining uses breathable mesh fabric. 【Included Items】 Water-cooling vest body x 1, USB battery x 1, USB Type-C cable x 1, Ice pack x 1 【USB Battery Specifications】 Battery Capacity: 3.7V/10000mAh Lithium-ion battery: DC5V/6200mAh Input: DC5V 2.1A (Micro-B/Type-C) Output: Type-A DC5V 0-2.1A (2 ports) Size: Approx. W64 x D96 x H26mm Weight: Approx. 182g Full Charge: Approx. 6 hours 【Materials】 Outer fabric/Lining: 100% Polyester Unit Outer Fabric: 100% Polyester Unit Lining: 100% Nylon Double-sided TPU processing Included Ice Pack: PE+PET Suitable Water Volume: Approx. 500ml Weight: Approx. 600g (excluding battery) Operating Time: Approx. 6 hours (when using the included 10000mAh battery) Size: Free size (unisex) Chest: Approx. 82-126cm Shoulder Width: Approx. 35cm Front Length: Approx. 55cm Back Length: Approx. 50cm