Not trying to dissuade (or suade) anybody - just chiming in with my experience. I have a basic versaflow helmet (I think its a 107) with the high impact lens, shroud, and specialized tube (the tube is expensive!). I extended the tubing with some cheap CPAP tubing. I also have an inline fan in a completely separate part of the garage, and off the shelf PVC tubing. Fan draws clean air (no filter needed) drives it through PVC/tubingtubing, into helmet, down across my face (no fogging!), and out the base of the shroud. I am tethered, but the tubing reaches everywhere in my space (or I could add another length). This was relatively cheap to set up/install, and has no filters to clog or replace. The versaflow is relatively light and well balanced - I can wear it for extended periods much more comfortably than even the Bionic shield with no tubing. Works for me. Copied Jerry Kermode's setup - he brings the air all the way from his house, so it's warm/cool, plus - he gets to smell whatever's cooking.