FOREWORD: This specification was prepared by the API Committee on the Standardization of Pumping Equipment and Engines. This Specification Provides: (a) Complete interchangeability between manufacturers on polished rods@ bore of stuffing boxes@ pull rods and pull rod couplings (b) Standard openings in screened or slotted pipe with standard method of designation. (c) A recommended standard assembly of wellhead pressure gage taps and fittings to avoid Confusion and delay m the field.