Product review (3 stars): Wished I'd just gone to the local hardware store...
So I bought this to hook up the Culligan water filter.  When it came right down to it, I didn't really want to puncture a copper line--some say you can get leaks that way.  I ended up going to the local hardware store (not a big-box home improvement store) and getting some advise.  Worked out nicely.  The compression fitting I tried to use from this kit didn't work very well.  So, I'd say don't bother...