Lenox Bi-Metal recip blades are the best by far for metal cutting - they have small teeth, and some blades are pretty stubby (ie less flex).
Dip the blade in water if it gets too hot.
Dont use the blades shown above for metal cutting.
I suspect that @JohnD only posted the image to show the fitting end of his blades.
The Rems Special blades mentioned above seem to have a proprietary fitting (or rather, one I have never seen).
