These knipex 97 53 08 crimping pliers for end sleeves are self adjusting to the desured end sleeve size they fit all twin ferrules within the application range you always get the best value and highest quality in crimping due to the integral lock on these pliers self releasing mechanism the crimping pressure is already precisely calibrated but it can be re adjusted pliers are made of chrome vanadium electric steel in special quality and they are ail hardened