These easy-to-assemble racks are designed for stable use in water baths. With alphanumeric grid reference aids for tube identification. The racks are shipped flat. The wells for 15 ml tubes have a Ø of 17 mm. The wells for 50 ml tubes have a Ø of 28 mm. - 30 wells for 15 ml tubes. - 20 wells for 50 ml tubes. These easy-to-assemble racks are designed for stable use in water baths. With alphanumeric grid reference aids for tube identification. The racks are shipped flat. The wells for 15 ml tubes have a Ø of 17 mm. The wells for 50 ml tubes have a Ø of 28 mm. - 30 wells for 15 ml tubes. - 20 wells for 50 ml tubes.