Vest using four Peltier elements. Size M, with a snug fit made of stretch material. Purchased in July for 20,000 yen and used only for 2 hours x 2 days. I intended to use it regularly without any issues, but I no longer need it as the company provided a similar product. The set includes everything. The vest has been carefully hand-washed. There are no scratches or stains. - Model Name: PV555 - Size: M - Cooling Temperature: -23°C - Heating Temperature: 50°C - Battery Capacity: 14000mAh - Input: USB Type-C