Filter inside low flow modules 800518 & 800519 Back Catalog number: 201119 Manufacturer: SENSIDYNE Availability: In the manufacturer's stock Price on request - + Recommended 6075-0421-20 Screws, Low Flow Module (Pkg Of 20) Price on request 385-0114-01 Zero Cap, Black Rubber for Nephelometer Price on request 811-0944-03-R GilAir Plus, STP to STP BlueTooth and Motion Upgra Price on request