XPOWER X 3400 Air Scrubber HEPA Filter (X 3400 H35) Dema The Separator has an anti collapse Stainless Steel The Separator has an anti collapse ring built into it fixed 16 mm Not stocked — ask us Full size Hygrostick (POL4750) BLD4750HS — not stocked 12 mm BLD12DR Full size Hygrostick The 19 mm system is the one supplied in the Protimeter flooring kits and the one used for in situ relative humidity testing to ASTM F2170 CCW lists two HEPA filters for this machine: this H35 HEPA (paired with the CF35 carbon filter) and the thick HEPA filter X 3400 7 (16 x 16 x 2 in) CCW also lists an H35 HEPA and CF35 carbon filter for the X 3400