These racks are similar to 9259J65 series, but are half the size to accommodate tubes up to 25 mm diameter. They have a 4 x 4 array and are molded of glass-reinforced polyketone. The racks? thermal properties allow for both autoclaving and freezing. The three-tier design is molded in one-piece, and the lower tier is suitable for 28 and 30 mL Nalgene? Oak Ridge Centrifuge Tubes.