Polypropylene rack conveniently holds 16 filled, 1.5-mL microcentrifuge tubes in a 4 x 4" array for incubation at elevated or reduced temperatures in water or ice baths. Rack will float with a full load of filled tubes. Tubes are supported below the lip while conical ends are immersed in water. On benchtop, rack legs prevent bottom of tubes from touching bench surface. Molded-in handle allows convenient transport, agitation, and removal from water bath. Excellent temperature resistance from -70 to 100° C.