L4x4x.25 STEEL
Would be correct in my office.
Steel callouts here are by type...
SS=Stainless Steel
ASTM=mild Steel etc...
So what we have is.....
L4x4x1/4 SS-304L = stainless steel Angle
W10X39 ASTM-A36 = mild steel W-Beam
C10x20 ASTM-A36 = Mild steel Channel
The "L" identifies the structural designation, just like "W" stands for Wide beam or "C" means Channel...no need to repeat that.
Call out standard material types at the end of the structural identifier.....simple!