Balloons, small, set of 2

For experiments on the effect of air pressure, positive pressure, negative pressure or for vacuum experiments, for determining the volume of gases, for qualitatively determining the density of air, for demonstrating the recoil of escaping air, for measuring the pressure in a balloon;
Two very robust, thick-walled balloons
Diameter (inflated): approx. 28 cm each
Diameter (opening): approx. 14 mm
Mass: 5 g