I have a medical condition that makes me particularly sensitive to cold temps and I would not be able to keep skiing without the ass gasket. Last winter we were in the Canadian Rockies and temps were in the low teens on an uncovered chairlift. I was totally comfortable though my family was chilled to the bone.
It fits easily under my snow pants which are fitted, without showing through, and is easy to take on and off. Plus the name is hilarious. Highly recommend.