the infusion set the infusion set is now applied into the body by the spring force of the pretensioned levers the distance u201c d 2 u201d shown in fig9 a between hammer head and infusion set after release does not have to be defined depending on the curvature of the skin at the application site the infusion set is in contact or not in contact with the hammer after the puncturing procedure the insertion device can be removed from the application site and the application procedure is completed in a further variant not shown in the figures but which can be understood therefrom and from this description the infusion set is not secured on the housing in such a way as to be struck off it by the hammer head and instead the infusion set is attached to the hammer head itself this means that the upper end of the infusion set is brought into connection with the lower end of the hammer head this can be done for example by adhesive bonding frictional engagement or a form fit in some cases the infusion set can be plugged onto or into the hammer head in this case the hammer head can for example have an extension which engages into a corresponding recess in the infusion set for example with an exact fit to hold the infusion set by frictional engagement.