Replacement for Briggs & Stratton Air Filter 491588. Fits Briggs & Stratton 4-6 HP Vertical Shaft Engines, and 3-5 HP Horizontal Shaft Quantum Series Engines 121700, 122700 and 124700. Air Filter Dimensions: 5-1/4" x 4-1/2" x 1" Item: BAF-119 O.E. Replacement Part Number: 491588 , 491588S , 399959 , 5043 , 5043B , AM116236 , LG491588 , LG491588S , PT 15853 , 100-988 , B1SB2838B , 12941 Features Fits Briggs & Stratton 4-6 hp vertical shaft engines, and 3 and 5 hp horizontal shaft Quantum series engines 121700, 122700, and 124700 Replaces Original Equipment Part# 491588 Paper Air Filter