These crimpers are perfect for the ferrules that we include in our m.unit wiring kits. Why do you need a set of ferrule crimpers? Installing ferrules on your wire ends is important so that you will not fray or damage the wire strands when inserting them into terminals or tightening down screw posts and helps to ensure you have a solid connection inside the terminal. You may be able to come up with some other way to accomplish the task but the result will never be as good as having the right tool for the job. The self adjusting mechanism allows for ferrules from 23-10 awg while the ratcheting action within the crimper allows for tight perfect crimps everytime requiring only 50% of normal hand strength and the resulting four sided surface allows for maximum electrical contact. Highlights: Ergonomic grip design crimping range 23 AWG to 10 AWG, both insulated and uninsulated wire ferrules and end sleeves Self adjusting, automatically adjusts to the appropriate ferrule diameter Oil hardened manganese steel crimping teel provide long life Ratcheting mechanism reduces required hand strength by 50%