A-AF937-AI Filter, Air, Secondary (QTY 1)One New Aftermarket Replacement Secondary (Inner) Air Filter Fleetguard AF937 This secondary air filter (also called an inner or safety element) provides a critical second line of defense in the air filtration system, protecting the engine from fine dust and debris that may pass through or bypass the primary outer element. The AF937 is a Fleetguard specification secondary air filter designed for use in Fits Case IH large frame tractors. Replacing a