The Circle Cutter Set consists of the optional Guide Rail Base Adapter and Circle Cutter for the Carvex jigsaw. This base can be used to adapt your Carvex jigsaw to a Festool guide rail to get extremely straight cuts. When used with the Carvex, it can be attached to a guide rail to cut in either direction. The circle cutter for the Carvex jigsaws can be used to cut a circles up to nearly ten feet in diameter. Works with all Festool Carvex jigsaw models.