schematically such as for instance mandrels or hooks and the like which secure the expansion element 26 the fastening means can also be arranged on the side edge of the second leg 24 and can be configured for example in the form of hooks that are facing the expansion element 26 in order to be able to build up sufficient intumescence pressure it is advantageous if the device 10 according to another embodiment has a shell formed by the anchoring element 20 with the expansion element 26 being arranged in the shell fig3 shows such a device 10 in a simplified perspective view for purposes of fastening the device to a wall or floor ceiling the first leg 22 of the anchoring element 20 is provided with preferably stamped fastening openings 36 the device 10 can preferably be stamped out of a strip of sheet metal and bent into the desired shape fig4 shows such a device 10 in a schematic top view along the sectional edge b b from fig3 the second leg 23 of the anchoring element 20 is provided with side tabs 32 that extend in the direction of the expansion element 26 the side tabs 32 can prevent the expansion element 26 from being squeezed out at the sides so that a sufficiently high intumescence pressure can build up in the shell 34 fig5 shows another schematic sectional view of a device 10 in which the intumescent material 5 of the expansion element 26 has expanded due to the action of the fire as a result of which the expansion element 26 was activated and the firestop collar 4 was pushed out of its original position the intumescent material 5 of the firestop collar 4 has expanded in the.