body 1 has an indent which is also formed at the connecting location between the inflatable body 1 and the bottom part 2 in order for it to be possible for the cord at the bottom of the inflatable body 1 also to be guided around the button strip clamp 3 along the indentation two further rear fastening devices 9 are disposed behind the rear corners of the substantially rectangular cross section of the button strip clamp 3 the fastening devices 9 are likewise illustrated in section in fig6 and as shown they have the same cross section as the fastening devices 8 the horizontal legs of the rear fastening devices 9 however are directed inward into the interior of the pressing dummy pointing towards the rectangular opening 4 it is disadvantageous however that for the purpose of fitting the inflatable body 1 the cord has to be positioned behind the button strip clamp 3 in the rear fastening devices 9 from the rear this is made difficult for a user by the button strip clamp 3 which is in the way and in addition blocks the view in order to remedy this disadvantage a shaped part 13 is fitted at the edge of the opening of the inflatable body 1 fig3 illustrates on an enlarged scale that region of the bottom.