Air filter for attachment to a fan grill
FIG. 1 is a perspective view of the air filter according to the present invention and shown attached to a fan grill; 
     FIG. 2 is an enlarged front elevation view of the air filter shown in FIG. 1; 
     FIG. 3 is an enlarged back elevation view of the air filter shown in FIG. 1; 
     FIG. 4 is an enlarged left side elevation view of the air filter shown in FIG. 1, the right side elevation view being a mirror image thereof; 
     FIG. 5 is an enlarged bottom plan view of the air filter shown in FIG. 1; and, 
     FIG. 6 is an enlarged top plan view of the air filter shown in FIG. 1. 
     The broken line showing of a fan grill in FIG. 1 is for illustrative purposes only and forms no part of the claimed design.