This standard applies to portable@ handheld@ internal combustion engine-powered machines@ which use a rotating cut-off (abrasive) wheel that is center-mounted on and driven by a spindle shaft@ and designed for cutting construction materials such as asphalt@ concrete@ stone@ and metal. The requirements in this standard apply to machines using up to 16 in (400 mm) nominal cut-off wheels. If the machine is designed for larger than 16 in (400 mm) nominal cut-off wheels@ the requirements of this standard shall be considered. The requirements listed may apply to machines designed for larger cut-off wheels. Cut-off wheel design and safety specifications are not included in this standard. The effective implementation date of this standard shall be two (2) years after the publication date and shall apply to all products built after that date. Manufacturers may also comply with the requirements of this standard any time after the publication date. ??ANSI/OPEI B175.4-2018?? and ??ANSI B175.4-2018?? may be used interchangeably wherever referenced or required in this standard.