Shim-Pack XR-SILICA HPLC Column, 3.0 x 75 mm LC Column, The Shim-Pack XR columns have a 2.2 micron particle size for high resolution at elevated flow rates without extreme high pressure. Silica particles of uniform size distribution result in rugged column performance, providing excellent peak shapes, durability, and longevity. Each column includes a performance report and physical properties certificate. Particle size 2.2 µm, pore size 12 nm. Carbon load approx. 10.5%. Optimum pH range from 2-7.5, operating temperature to 80C, maximum pressure 35 MPa (5100 psi). Male nuts 228-45717-01 and double ended PEEK ferrules 228-45717-02 are recommended for column installation.