These knipex 250mm alligatorreg 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 the plastic coated handles have slip guards for extra safety they also have a 39no nip39 feature which prevents the handles locking together and dama