1. American Air Filter
2. Camfil Farr
3. Freudenberg Group
4. Donaldson Company Inc.
5. Clarcor Inc. (NYSE:CLC)
6. Sogefi Group (SO.MI)
7. MANN+HUMMEL
8. W. L. Gore & Associates Inc.
9. Ahlstrom Corporation (HEL:AHL1V)
10. MayAir Group plc (AIM: MAYA.L)
11. 3M Purification Inc.
12. Neundorfer Inc.
13. Dafco Filtration Group
14. K&N Engineering
15. Denso Auto Parts
16. APC Filtration Inc.
17. Koch Filter Corporation
18. Alen Corporation
19. Austin Air
20. FLSmidth