Papco #600 Roto Master Tube Flaring Tool
 

I have two of these. Haven't tried using them yet. Both are in very good condition, and are complete with all dies. Missing instructions, but found instructions on line.

Can flare tubing from 1/8 to 3/4. Supposedly does either single or double flares on everything from copper to SS.

Research indicates they were used in Aircraft as far back as WWII to make emergency repairs. The nub on the end fits into a vise to make it easy to use.

Anyone ever use one? Anyone know anything about them?

Found one YouTube video. Skip to 5:31 to see the flaring tool.
https://www.youtube.com/watch?v=zDlEQoVWWfQ

A few for sale on ebay.

If they were for aircraft, guessing 37* flare and not the 45* typically in cars/brakes?