This Durable Plastic Elementary Balance Scale is a great science tool for teaching young scientists the basic concepts of mass and mass measurement using plastic and metal weights. Graduated plastic buckets to measure liquids and density.Suitable for Ages 4 and up. Balance has a plastic slider that zeros the balance. Fitted tray lids convert buckets to make platforms. This set includes: Plastic Bear Weights 4 – 12 gram 4 – 9 gram 4 – 6 gram12 – 3 gram Metal Weights 1-50 gram2-20 gram2-10 gram2-5 gram2-2 gram1-1 gram WARNING:this item contains small pieces that can be a choking hazard for young children. Adult supervision is required at all times.