BrandTech 4340022 20mm 40 Tubes Red Polypropylene Test Tube Rack, 4 x 10 Tube, -20 to 90 Degree C Operating Temperature (Pack of 5) Accommodates 40 tubes with a diameter of up to 20mm; red Tube position format: 4 x 10 Polypropylene rack snaps together for easy assembly, sturdy construction, stackable, and is available in four colors Will not float in water bath; alphanumerical positions for clear sample identification Wide spaces between positions; operating temperature -20 to 90C; autoclavable at 121C