The only downside is the tool needs to be mounted in a vice, so you can't use it on the vehicle. Still it will do double flares and bubble flares in a bunch of common sized brake line sizes.

A file taken to the edge is a good idea as well. 6. To make perfect 45-degree single, double, and bubble flares, we use Eastwood's Professional Brake Tubing Flaring Tool exclusively in our tech ...

Flaring metal brake lines and metal fuel lines (or transmission lines) is something of an art when using the most common type of double flaring tool. We're talking about the mass-produced double ...