These are new in box. There are 4 filters included, each measure 14x20x1. Description manufacturer: High Performance: The Filtrete Premium Allergen & Ultrafine Particles Filter is designed to capture microscopic particles like nano-particles, bacteria, and viruses, as well as larger particles like mold spores and pollen. Optimal Air Quality: Helps improve your home's air quality by proactively capturing dust, bacteria, viruses, and allergens, contributing to a cleaner, fresher home environment. Microparticle Rating: Features a high MPR (Microparticle Performance Rating) of 2500, ensuring effective capture of microparticles such as pollen, pet dander, smoke, bacteria, and viruses. Durable Use: Each filter lasts up to 3 months, making it a cost-effective solution for maintaining optimal air quality in your home. Exclusive Technology: Designed with Filtrete Brand 3-in-1 technology from 3M to trap unwanted air particles while allowing cleaner air to flow through. Residential Use