Opt for a Filtrete Allergen DefenseAir Filter to transform your central heating and cooling system into a whole-home air filtration operation. This no-nonsense filter helps capture varying sizes of particles, from the large (lint, pollen, dust and pet dander) to the microscopic (smoke and smog). Type: Pleated Electrostatic Material: Synthetic Size: 18 In. x 24 In. x 1 In. Actual Size: 17.81 In. x 23.78 In. x 0.84 In. Rating: 1000/1085 MPR Life of Product: 3 mo