Podoy 394018 Air Filter for Briggs & Stratton 394018S 392642 30-101 100-131 ROTARY 2777 Lawn Mower with Pre Filter package includes 1 pc air filter + 1 pc pre filter Fits 16 & 18 HP horizontal engines 402400, 421400, 422400 series Replaces Briggs & Stratton Air Filter Part Number 394018, 394018S, 392642 Pre-Filters Replace Briggs & Stratton 272490, 272490S ID: 5-5/8", OD: 7", Height: 2-1/4"