Tubing

by knowing the age, and where it was made helps.
it won't be a really heavy frame either, nor superlight.

I don't get the obsession with 531, it's old hat and not that special
crap. where did the term vintage lightweights came from. 531 is awesome tubing, my old holdsworth mistral from the 60's, was feather light even with chromed ends.

531 is double-butted (thick tubing at ends and thinner in the middle). if you tap your nail alongthe tubing it will change sounds in the middle, more tinnier.