Frey Scientific Economy Free Fall Tube demonstrates how objects fall at the same rate in a vacuum, despite differences in mass. Tube measuring 90 centimeters (or approximately 35-2/5 inches) in length and 4-1/2 centimeters (or approximately 1-1/3 inch) in diameter is made of tough, clear plastic with rubber end caps and hose cock for connection to any standard vacuum pump (not included). An included disc coin and feather provide the perfect “drop” objects to see this theory in action. Activity guide included.