This part of IEC 60153 specifies straight hollow metallic tubing of ordinary rectangular waveguide for use as waveguides in electronic equipment. The aim of this recommendation is to specify for hollow metallic waveguides: a) the details necessary to ensure compatibility and, as far as essential, interchangeability; b) test methods; c) uniform requirements for the electrical and mechanical properties. It should be noted that no recommendations are made for the materials to be used for waveguides. The choice of material must be agreed between customer and manufacturer.