The present invention provides an improved top spin valve and method of fabrication. For most purposes, the sintered part is indistinguishable from another part having the same dimensions made by isotropically molding the powder. The optical transmitting and receiving device is preferably inserted in a monolithic manner into a common substrate, comprising a sequence of superimposed layers for the light emitting transmission element and the light receiving element. A rack mountable surge suppression unit provides local in-line surge suppression protection for the electrical equipment located in the communication station. The polymers are useful as molding resins and elastomers. and at the same time a reduced pressure of 10 mbar to 800 mbar is established in the reactor by removal of the inert gas or carbon dioxide, under an atmosphere of inert gascarbon dioxide mixture or under a pure carbon dioxide atmosphere, alkylene oxide is added to the mixture from step at temperatures of 50 to 200\xb0 C.