<p>The device serves for blow molding containers. Preforms of a thermoplastic material are heated in the area of a heating section and are subsequently transferred to a blow device. The blow device is provided with at least one blow station for deforming the preforms into the containers. The preforms are held along at least a portion of their transport path by a support element which over at least portions is loosely inserted into an opening section of the preform and is tensioned after the insertion within the opening section. Along an outer circumference of the head are arranged at least two clamping elements at a distance relative to each other.</p>