Steel Bras?

[annie]

Looking around the net, not really searching for any one thing I ran across pictures of steel bras. OK, maybe I'm a bit naive here but for some reason steel and bra never equated in my mind other then Madonna's corset cones.

Has any one tried these?
Are they comfortable?
What are the drawbacks with them?
Is it something you would like to try?
Something you would like to have your sub try?

And maybe I'm missing something but what exactly would be the purpose for them? Just looks? Chastity in a way? I can certainly see where it would resolve and "sag" problem but past that?