Filter inside low flow modules 800518 & 800519 Back Catalog number: 201119 Manufacturer: SENSIDYNE Availability: In the manufacturer's stock Price on request - + Recommended 811-0920-01 Replacement Valve Caps (Pack of 2) Price on request 811-9927-03 Cyclone, BGI4L Replacement Screw Kit Price on request 910-0910-NO-R GilAir-Plus Data Logging Single Starter Kit, Bluetooth, No cord Price on request