The Aven Tools 10187 Crimping Tool for Wire Ferrules (4 and 2 AWG) features a built-in ratchet that applies the pressure necessary to ensure a complete crimp every time. The crimper is equipped with a safety release function that allows you to stop a faulty crimp before the crimping cycle is complete. The precisely milled, hardened steel dies have individual crimping slots for large insulated ferrules AWG 4 and 2. The dies can easily be changed by sliding them out of the frame - no tools are required. The durable rubberized grips make the crimping tool comfortable and easy to use.