Free-size cool vest that provides both cooling and heating. Equipped with a 15000mAh battery, it achieves a cooling effect of approximately 8°C and a heating effect of approximately 43°C. - Brand: NAFCO - Cooling effect: Approximately 8°C - Heating effect: Approximately 43°C - Battery capacity: 15000mAh - Size: Free size - Model name: Cold/Heat Switching Vest - Number of devices: 4 devices I tried it out for about 15 minutes. Please understand that this is not a new, unused item. Thank you for looking.