HFF Black Steel is based on Acier Noir, from page 1 of
"Moderne Alphabets: 100 Complete Fonts" by Dan X. Solo,
first published by Dover Publications in 1999. Acier Noir 
is also listed on page 55 0f "The Solotype Catalog of 
4,147 Display Typefaces".

HFF Black Steel is a free font. You are free to use this 
font in any way you want to. You can share this font with 
others if you wished to. 

Use freely, share freely and, most of all, enjoy the font. 
