The first important thing to know is how this thing works. First you will find that it uses the same principle as a standard ruler, which basically has a square or rectangular shaped base. Then there is an extended part that makes it very useful for measurements in the length department. There is a threaded portion that fits onto the rulers that will allow you to fasten it securely on to the electrical outlet. You simply will need to pull this out and connect it to the length of cable that you are measuring.
Then you can use this thing to measure anything that you might want to know about. It can easily fit inside of a tool box if you do not have one that is very large. You can also easily find a local shop that will sell it for you. If you would like to see how to use it, all you need to do is click on the link below.