The development of a new type of stopper rod, Argorod, makes it possible to improve the steel quality during continuous casting. The main results that have been obtained concern the tightness of the joint : the new Argorod system, of second generation, has a better tightness, the assembling operation is simplified and more reliable; the optimization of the system for argon introduction: sized tube, more accurate adjustment of the couple argon flow rate / back pressure ; the accurate control of steel throughput: choice of the nozzle shape factor “material strength / stopper rod weight”: weight saving for the same or for a higher transverse strength.