Fits Briggs & Stratton 4-6 HP vertical shaft engines, and 3-5 HP horizontal shaft Quantum Series engines 121700, 122700 and 124700. Helps prevent dirt and dust from reaching the engine. Replaces OE# 491588, 491588S, 399959, 5043, 5043B, AM116236, LG491588, LG491588S, PT 15853, 100-988, B1SB2838B, 12941.