Comfortable and warm
Very comfortable, slim(not bulky) warm. Only complaint is one of the velcro pieces is falling off after 7 days.
4 carbon fiber heating elements generate heat across the core body areas (left & right chest, mid-back and neck). 3 heating levels for adjusting by pressing the button. (High, Medium, Low)
Up to about 9 working hours and heat quickly in seconds with 5V and USB port to connect battery.