This part of IEC 60153 specifies straight hollow metallic tubing of circular cross section for use as waveguides in electronic equipment. The aim of this recommendation is to specify the 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 is to be agreed upon by customer and manufacturer. This document should be read in conjunction with IEC 60153-1, which gives general requirements and test methods.