No luck finding that C4(at acceptable price); so going to use the C3 that I have.
This is the mask. 
Have no filter can. so far have removed the front valve to allow easier breathing. This introduces a new problem. The lenses now fog up as the air path keeps them from fogging. to fix the fogging I will be building a fan module that connects to the filter inlet. The other mod has been to replace the straps with magnets that will clip onto the hood piece. (no hood piece done yet).
Guess I have to get onto the photo thing. Am out for 2 weeks. proper things to happen then.