From what I can gather the MR94A is the same dimensions as the MRII594A. Also from pictures I have found I think the MRII594A does not have a detachable throat, the MR94A has the detachable throat? I also think they are made of the same synthetic material, not metal as some of the early Mantaray horns were? As far as asthetics I can see very little difference. I have spent some time investigating these horns and have not found a great deal of detailed information or home user reviews. Notice all the ? marks and I thinks, I've been looking but there just is'nt a lot of information out there.