5 Micron Pre-filter for Pura UV20 series. 20" long. Replace every 3-6 months or as needed. Pura Part #33003033. We are distributor for Pura products. Filters styles and appearance may change slightly due to supplier stock however the filters are always 5 micron rated and will fit the UV20 Series.
For an instructional video on how to change your lamp and filters, please view here: https://www.puriteam.com/pura-uv20-service/