The invention is based on a device having a centering element (10) and at least one form-locking element (12) for fastening an axially mountable tool (14) to a drive shaft (16), which is drivable in an oscillating manner, of a hand-held power tool (28) in which the centering element (10) is provided for centering the tool (14) relative to the drive shaft (16), and the form-locking element (12) is provided for defining a rotary position of the tool (14) relative to the drive shaft (16).It is proposed that the form-locking element (12) is located radially outside the centering element (10).