Abstract: An improved unitary fin structure for installation on the filter element of an air pre-cleaner and final filter for an internal combustion engine or the like. The improved fin structure includes self-biased lock tab elements forming an integral part thereof for securing the fin structure to a conventional air filter element while providing means for the non-destructive removal thereof from the filter element. An alternate embodiment of the fin structure of the present invention provides for the manufacture of the fin structure in a substantially flat strip with coupling means on the opposite ends thereof for assembling the strip into a substantially cylindrical configuration at the time of installation on the filter element. Various forms of coupling means for engaging the opposite ends of the strip are also disclosed.