this jacket is very light in weight i have 2 other down jackets both at 80% down and they are much heavier than this, but that do not take away from the heat this jacket gives. It actually feels like you have a low wattage heater in the coat i read about the tech on the trespass web site but didnt understand very well something to do with the wind and rain blar blar blar but i gotta say it works. this is a great bargin and an even better price 80% off the trespass price wow this jacket was great until washed it has run even though it states that it should be washed at 40% so now this jacket is a pale pink and in some places it is more pink and my set of white towels have blotches of pale pink all over them so now i see this as a not so good buy