Just picked one up. Looks and feels decent enough. Made of cast aluminum so definitely not milspec. Very small. Looks like the bend radius is 1/2" to 9/16". I'll be testing on some steel tubing this evening.
This is the one I have. LINK Bends steel brake line no problem. Haven't tried thickwalled ss tubing, but I imagine it would handle it fine just might bend a little harder. Cheaper than Carl's.