Inogen One G2/G3/G4 Output Filter Replacement Kit - Newegg.com
Synthetic bag filter G3-G4
Inogen One G4 Output Filter Kit: RP-404
10pcs/lot Lab Clear 30ml 40ml Glass Sand Core Crucible with G1 G2 G3 G4 G5 Pore Size Filter for School Experiment|Beaker| - AliExpress
Amazon.com: 12Pack CF Clean Fairy Vacuum Filter Bag Compatible with Kirby G3 G4 G5 G6 G7 Style III & Heritage II Replacement for Part#197294 197394 : Home & Kitchen