The reversible tube rack 96 well by Heathrow Scientific is made from polypropylene. The tube rack has 96 wells for 0.5 mL microcentrifuge tubes on one side and 96 wells for 1.5 to 2.0 mL microcentrifuge tubes on the other side. Wells are arranged in standard 8 x 12 array. Handy lid snaps into place via tabs on each end of rack. 0.5 mL wells are separated by molded-in grid lines, making them easier to see, and raised rings are around the 1.5 to 2.0 mL wells make tubes easier to remove. Autoclavable. Specifications: Tubes: 1.5/2.0 and 0.5mL, Wells: 96, Well Diameter: 11/7.6 mm, Dimensions: 9.6 x 4.7 x 2 in (24.6 x 12.1 x 5 cm), Color: assorted colors: blue, green, pink, yellow, and orange, Quantity: 5 per pack.