The invention relates to a component such as a rotor or stator for an electrical machine. The component includes a plurality of axially adjacent stacks of laminations. At least one pair of adjacent stacks are spaced apart in the axial direction by spacer means such that a passageway or duct for cooling fluid, e.g. air, is formed therebetween. The spacer means comprises a porous structural mat of metal fibers. The cooling fluid may flow through the spaces or voids between the fibers.