Each 96 deep well rack comes with 1.2 mL cluster-strip tube and cap assemblies. Each tube is pre-filled with 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.These Lysing Matrix racks are optimized for the FastPrep™-96 Instrument and are included in the FastDNA™-96 Tissue and Insect DNA Kit, and the FastDNA™-96 Plant/Seed DNA Kit