This Stens Replacement Air Filter/Pre-Filter Combo combines the best of value and performance, blocking dust, pollen, dirt, insects and other contaminants from entering the engine, while also allowing sufficient amounts of air to flow through the engine system. To operate optimally, your engine needs to be free of all of those contaminants, while still maintaining air flow to allow the internal combustion engine to work at maximum efficiency. Stens is a recognized name in the outdoor power equipment industry, and has earned a reputation for producing best-of-class quality replacement air filters. With a Stens replacement air filter equipped, owners of outdoor power equipment can expect enhanced performance, reduced engine wear and efficient operation of their machines. Manufactured with an exact-fit design, every replacement air filter is made to match the original OEM air filter used in outdoor power equipment. This perfect fit ensures high-level protection for the engine and simple installation of the air filter. As best practice, air filters should be replaced on a regular schedule, or sooner if environmental conditions require it.