Round test tube rack 

These racks are designed to rest firmly and steadily into ice buckets listed. Made of expanded PVC that grips test tubes firmly, yet allows easy insertion and removal. Racks will float in melted ice, dry ice/alcohol slurry, and liquid nitrogen. Custom cut a disc blank into smaller circles, halves, quarters, or other shapes to permit the addition of other vessels into the same bucket. The rack with 30 large 17 mm diameter holes is for 15 mL conical tubes or 13 mm Falcon tubes, and the rack with 44 small holes is for 1.5 mL microcentrifuge tubes.