The majority of plates in the plate package are channel plates, and it is between these plates the heat is transferred. Generally, the channel plates are symmetrical and 4-holed creating the parallel flow of the two fluids. The identical channel plates, with one plate design and one gasket design, are named A side or B side depending on if the chevron pattern is pointing downwards or upwards. Every other plate is hung upside-down creating the open flow channels where the corrugation provides mechanical strength in the supporting points.