Amazon.com: Spectre Performance (4806) 6-3/8" x 2-1/2" Air Filter : Automotive
Three Stage Air Drying System SAU430-N04, 1/2" NPT, PneumaticPlus SAU Series
Filtrete 21.5-in W x 23.5-in L x 1-in 11 MERV 1085 MPR Allergen Defense Extra Electrostatic Pleated Air Filter (2-Pack) in the Air Filters department at Lowes.com