Air Filter for Lawn-Boy Walk-Behind Mowers. Fits F Series Engines. Air Filter Dimensions: 4-1/2" x 2-1/2" x 1-1/4" Item: LAF-120, 609493 O.E. Replacement Part Number: 609493 , 107-4621 , 100-586 , 1380 Features Fits F series engines Replaces Lawn-Boy OE #609493 Contains one air filter