I worked as a cable man for about a year and in that time I used three different Tone & Probe kits. They ranged from the cheap $30 T&P's to the Fluke Filtered T&P featured on this Amazon page. Here is my 2 cents, if your a DIY home repairman and will only use this tool once or twice a year then get the cheaper T&P's on the market. If this is your job and you're day to day, week to week, or even month to month requires you to tone lines out...Get a Fluke. Your reputation depends on a tool that won't make you look stupid in front of the customer. I've worked on active networks with PoE, to running phone lines, and Coax. The Fluke just works (if you know what you're doing). On active networks this becomes difficult, since your networking equipment is designed to filter out unwanted signal (including your tone generator). The trick is to use a banjo and only connect one of the alligator clips (Not Both) to keep your signal from getting grounded out on Active networks. I no longer work for the ISP as a Cable Man, I now work for myself. The first thing I did was buy the filtered T&P from Fluke. The toner is light enough to hang off existing runs without fear and is loud enough that you won't 2nd guess yourself. Even in bundled networks with 100's of runs I can quickly find the exact cable I need to complete the job. The ability to change tone by touching the wires together verifies (even with signal bleeding into other wires) that you have the correct cable. The headphone jack is a life saver when working in loud server environments. It's a handy tool that has plenty of applications. As always though, your work requirements might be different. As I said earlier, if your a DIY person who won't be using this tool often, save your money and get something cheaper. They'll work. If your reputation is on the line and you'll be using this tool often, get the Fluke. It's a verified certified product with all the documentation you'll ever need. You will not be 2nd guessing your work if you know what you're doing. As a fallow up, I don't use this tool to probe electrical wiring as I'm not installing electrical outlets. There are better tools suited for that job, but this can work in a pinch. On that note, I've had to repair so many runs that were done by electricians that didn't know what they were doing that it's not even a joke. Not trying to talk down electricians, just emphasizing the fact that you should really know what you're doing before writing a bad review about this product.