These racks are designed to hold Labcon centrifuge tubes. Unlike foam racks, they are autoclavable and will not fall apart with repeated use. They can be frozen, and they stack together to minimize storage space. An interlocking design lets you connect more than one rack to create a handy work station. Autoclavable (122°C) and freezable (-80°C). These racks are designed for Labcon centrifuge tubes, other tube brands may not fit correctly.