As has already been mentioned, this style sucks. It is nearly impossible to hold the tubing tight enough to flare it without the tubing sliding down. I still have a couple in my tool box(s) but I haven't used them in decades.
Instead, I've been using a K-D 2190 flaring tool for years. It's good when you get into tight places and, unlike the parallel-strap versions, it securely clamps the tubing when you're flaring it.
When Gearwrench took over K-D Tools, they discontinued it but they're still out there on ebay.
Don't forget to dress the new flare with a lapping tool.
That'll get rid of any imperfections in the surface of the newly created flare.
There are a pair of stones in the kit. One for 37 degree and another for 45 degree flares.
It's a Koul Tools Surseat P-51
If I'm flaring tubing on the bench, I use my hydraulic flaring tool but it's kinda clumsy to use if you're repairing a line while the tubing is still on the vehicle.
I also have one of the aforementioned vise-mounted flaring tools but they're useless if there's no vise around to secure them. They're best suited for a fabrication shop, especially if there's not enough room surrounding your vise to accommodate a long steel line.
And....
If you need to make tight bends really close to the flare nut, ECI makes a vise-mount tubing bender that works great.
ECI Tubing Benders Catalog Page - Engineered Components, Inc.
