For lower altitudes, the BLACKYAK Bakosi Jacket is an outstanding product. It features intelligent insulation mapping: where the body needs more insulation to stay warm, the insulation chambers have been engineered to create more insulation. In the sleeves the chambers get smaller, as less insulation is required. Inside this jacket, the padding level of the chambers also varies. There is traceable goose down (750 cuin) over the top area of the body for maximum warmth. At the lower parts of the arms and in the belt area, PrimaLoft® Gold has been used as its hydrophobic properties make it ideal for this. For the back panel, where more permeability is needed and stretch is vital for maximum freedom of movement, Polartec® Alpha® has been used.