These Guard Column Cartridges are packed with 10µm, Cogent NP Silica™ Stationary Phase. This low metal content, 100A, very high purity Silica is not modified in any way.They are designed to protect your NP Silica Semi Prep Column from particulate and contaminants that will adsorb to it. Packed in a Stainless Steel Tube, they have Stainless Steel Frits.Use these Guard Column Cartridges with a 10mm ID Prep Column Holder. Click HERE for more information.