Construction of this vest is very nice. I'm a tall, skinny guy (6'2", 160#, 36" waist) and still found the small size a bit big to really feel what heat this vest puts out. You can feel the 100% and 75% heat settings after a while, but not so much the 50 or 25%.
Heat rises, so I thought that the heating elements were/are placed too high on the vest allowing heat to escape through the collar. Maybe if the heating elements were placed lower, the heat would rise up the vest and body, more than what it does now, and therefore be more effective?
I liked the idea of a self contained heated vest, but ultimately I returned the vest to exchange it for a real 12 volt bike plug in model as living in NW Minnesota we need all the heat we can get! Uff Dah!