Glad I got my suppressors in, so I can hear the ping.
We’ve gotten word from the vendor:
The steel is stamped Steel with a 48/50 Rockwell hardness
I hope this information is helpful! 
Just got these in the mail last week, so far I have put over 200 rounds of 40 cal on them and they have held up great! I will most def. purchase again. NOTE THESE ones are the more expence of the two, rated for higher calibre, and are much heavier duty then previous woot listings. Sportsmens guide has the same targets on sale for $162 each currently.
Sorry for the (way) late reply. I ordered the Body Shot. Got a chance to use it this past weekend, liked it so much I just ordered 2 more during the woot-off.