Don't know about Guohua but I bought a Shen Hao 6x12. The only problem I have is the ruby red window is pretty dark. I bought some film that had black numbers on black paper. Lets just say I missed a few frames. Buying the Shen Hao direct from the factory is a pretty good deal at about $220 US. It comes with three masks so the back is really a 6x4.5,6x6,6x9 and 6x12. Mine looks well made if not overly complicated.