Very effective tool
I bought two of these to tie flouro leaders on my braided spinning rigs as well as tying tippets together. It works great once you get used to it and saves a lot of fussy fingerwork with loops that you generally need a third hand to easily manage. Definitely recommend if you are frequently tying lines together. You do have to be careful on thin tippet/flouro though as I have had it cut through the line a few times.