1- Lay the Sleeve with the zipper side down on a flat surface and remove the chest straps (C), then turn the Sleeve over so the zipper is facing up.
2- Lay the Heat Exchanger out flat, separate from the outer sleeve. Insert the Heat Exchanger into the Sleeve by feeding the connector through the opening (F) on the left shoulder. The blue side of the Heat Exchanger should touch the blue side of the Sleeve.