Zeus was legitimate, but never made a 300MH scrypt miner - ALL of their miners were quite a bit lower than that - and they never achieved the efficiency level claimed for that
monster.
till they said they were gonna make the 300 MH miner then they started ripping off a few some got paid back a few still haven't, then some one there was in law suit under a different name, i even bought a few of the low end ones, i wanted to upgrade that was one of the selling points of the so called volcano, yea they were legitimate til they went bad . The pictures every one sees was what it was suppose to look like, but any one can get them off of Zeuses site. So anytime i see some one any place trying to sell the volcano ,i steel clear of that site, after, i have a good laugh .
As many others said the 300 from Zeus does not exist. As a general rule if you see a rendering and no real product almost always it's a scam. Sadly many do this throw up a rendering... try to get pre-orders that never come.
The only rendering that I believe will hit market right now is B11 miner -
https://www.bw.com/pool/miner . They have a lot of backing and I think it will hit market eventually. But pretty much in most cases a rendering is sign of scam.