Our easy to use design enlarges existing holes to a wide variety of diameters for a wide variety of applications, including: Upgrading boiler flues.Upgrading gas pipes.Upgrading waste pipes / soil pipes.Upgrading extractor fans.Upgrading condense pipes.The inner spring-loaded core bit provides easy removal following the wall's outer core scarring, ensuring perfectly symmetrical holes to one another.The larger outer core is quickly released from the drill / arbor adaptor (not supplied) by simply removing the Clipacore Clip.