Guard column for any Allure Silica column with 2.1mm ID. Use with Level 2 or 3 Trident holder. 5um particle size, 60A pore size, 450m2/g surface area. pH range 2.5-8, maximum temp 80C. Use Trident Level 2 holder REST-27472 (guard column only) or Level 3 holder REST-27474 (guard column + filter.)