Ideal for junior high, high school and college labs. Sturdy heavy-duty construction, very stable, chemical resistant and easy to clean. Holds 12 test tubes up to 20mm in diameter and has 5 drying pins. Ideal for junior high, high school and college labs. Sturdy heavy-duty construction, very stable, chemical resistant and easy to clean. Holds 12 test tubes up to 20mm in diameter and has 5 drying pins.