Very nice set. I'm a high school science teacher and ordered this kit to demonstrate that different objects with the same volume have different densities when their masses are also different. (d=m÷v) The set I received included 12 samples: Polypropylene, Brass, Acrylic, Oak, Pine, Rosewood, Steel, Aluminum, Copper, Dense Wood(?), Nylon and PVC. The volume of each sample is very close to 25 cm³. mm/1cu. inches / 16.3871 ml. I gave this product 4 stars because the oak and pine samples in my kit are a bit small. These two samples have a volume of about 24 cubic millimeters.