Weight Rings (5 cm) comes with an internal diameter (ID) of 50mm (5 cm) and can be used for volumetric flask/measuring cylinder of 1000ml to 2000ml capacity. The weight rings are vinyl-coated and can fit over straight necked flasks. The weight rings are chemical resistant and give added weight to flasks to protect from spills. Rings are rubber coated to protect the glass flask from breakage. Weighted beaker and flask holders safely allow beakers and flasks to be submerged into a water bath while having access to the beaker opening. They can be stacked to save space or add height.