(Click to see larger image) Never worry about knocking over a rack of test tubes again! Our Super Polyester Test Tube Racks hold and lock your tubes securely and have a low profile which makes them virtually impossible to tip over. Not only are they lightweight - less than 2 ounces - but they float on water, even when full of samples. In addition, they are flame-retardant and chemical and solvent resistant. The rack for 0.5 - 1.8 mL tubes securely holds 30 microcentrifuge or micro blood collecting tubes. Each stretchy hole is approximately 4mm in diameter. Each rack is approximately 19cm x 12cm x 1.8cm and the hole pattern is 6 x 5.