The original Kohler kit containing the primary paper air filter and the corresponding foam pre-filter is engineered to the highest factory standards for single-cylinder engines. The main filter is made of special, densely pleated filter paper that provides the maximum surface area for stopping the finest dust particles and abrasive materials, while the outer pre-filter is made of premium high-density open-cell foam. This synergy of materials allows optimal and constant flow of clean air to the carburettor, which guarantees proper mixture formation and maximum combustion efficiency. Correct operation of this system directly prevents micro-particles from entering the cylinder, which drastically extends the life of the engine, rings and valves on tough terrain. In professional practice, inside agricultural machines and tractors working in extremely dusty environments, this kit endures the greatest loads. The most common causes of failure are irregular blowing out of the paper element, soaking of the foam with oil due to tilting the machine, and clogging of the intake pores with fine dust and sawdust. The main symptoms that the filter is fully due for replacement are a sudden drop in engine power under load, the machine choking when the throttle is applied, black smoke at the exhaust indicating an overly rich mixture (lack of air), and noticeably increased fuel consumption. Ignoring these symptoms leads to dirt being drawn past the sealing edges of the filter straight into the engine, which causes permanent damage to the internal components, so fitting a new original kit is the only reliable solution. Manufacturer: Kohler (Original) OEM catalogue number: 25 883 03-S1, 2588303S1, 235116-S1 Material: purpose-made micro-porous paper and high-quality open-cell foam Function: primary and secondary air filtration in the intake system Position inside the machine: Air Cleaner Assembly (air filter housing) Filter dimensions: outer Ø 160 mm, inner Ø 148 mm, height 43 mm Compatibility: this kit is intended at the factory for the following engine models and heavy garden machinery: Kohler K241 (10 HP) Kohler K301 (12 HP) Kohler K321 (14 HP) Kohler Magnum M8 (8 HP) and M10 models with the specific deep housing Suitable for tractors and machines of the Case, Ingersoll, John Deere and Gravely brands with these engines Field installation tip: Before fitting the new kit, completely and thoroughly clean the inside of the plastic or metal filter housing of accumulated grease and dust so that new dirt does not get into the carburettor. The foam pre-filter can be lightly moistened with a few drops of engine oil before being slipped over the paper filter and squeezed out well in a clean cloth so that it traps dust better. When closing the housing, do not overtighten the central screw (wing nut) so as not to warp the top cover and create a gap where the engine can draw in "false" air past the filter.