I just wired a new sub panel at my house and this was an absolute must have. I don't know why they don't sell these at big box stores because they should. Without it you have absolutely no idea of how tight or over tight or loose you have made your connections. I tried a few connections with a regular screwdriver and then checked them with this and found that I over tightened and flattened the wires which could cause them to break under stress and have a bad or unsafe connection which could create a fire. On the side of every breaker there is a specification for how many ft pounds of pressure they should be tightened to. Once you know this, you set your screwdriver to that specification and it will click when you achieve the correct torque, and you then stop and are done. Every connection is correct and safe and it's so easy to use. You really need to get this if you are doing any electrical work. I wish I had years ago. It's so affordable too.