This 13mm half-rack Unwire test tube rack is more space-efficient than full-size test tube racks. This half-rack holds thirty-six 13mm test tubes or centrifuge tubes in a 6 x 6 array. Fits easily in ice or water baths and won't float. It has all the features of full-size Unwire test tube racks. Molded in white acetal plastic with Resmer manufacturing technology which makes the rack keep its bright color longer. Useful in a wide temperature range with good chemical resistance. Autoclavable. Color: white. Material: acetal plastic. Dimensions (L x W x H): 102 x 102 x 56mm. Capacity: 36 tubes. Tube diameter: 13mm. Array: 6 x 6. Nalgene #: 5972-0013.