I have one

This tool works "okay", if you have used the 45 degree flaring tool of the same style there is no difference. Careful usage produces a reasonable quality fitting - never had one leak. However when I started in on the airplane fuel lines I used a Parker Hannifin that my hangar mate had; and then I went and bought one of my own. A little more expensive but almost fool proof (a good thing for me to use!).

The Parker has a setting for the depth of tube before you start flaring, and the point at which the flare is finished is very obvious, the tension escalates rapidly. Perhaps more importantly the Parker seems to be able to clamp the tube without leaving striation marks on it which would create a potential point of failure in a vibratory environment like an airplane.