These knipex 250mm cobrareg waterpump pliers are manufactured from chrome vanadium electric steel oil hardened and tempered with smoothly ground jaws joint faces and an accurately formed box joint with safety stop the parallelogram shaped gripping surfaces have specially hardened teeth to 61hrc for positive grip on pipes and nuts featured is one hand press button adjustment for ease of use the handles are plastic coated with slip guards for extra safety these pliers also have a 39n