Each impact-resistant 2 mL tube contains 2.0 mm diameter Yttria-Stabilized Zirconium Oxide beads. Y2O3 + ZrO2 has high density and has extremely high hardness making this matrix ideal for cracking of very tough cell walls, while it's smooth surface minimizes shearing. Lysing Matrix Z is used primarily for lysis of animal and plant tissue, tougher stems, roots and seeds, and whole insects. Matrix Z is an alternative to the very agressive Matrix A because it's lower shear rate minimizes degradation in applications such as RNA and Protein isolation from very tough tissue.