I am using the GVS Elipse Half Mask respirator with Hespa P100 filters. I purchased from Ebay $ 26.95 and free shipping, but amazon has it as well. It works really well, I like it because it breathes both ways and does not get hot like some of the masks. The only thing I found it sits close to my eyes on the nose piece and I have to tilt my head a little different when scrolling. probably just my big head. I believe this might be the same mask Steve Good was using.
grizz