Everything you need to experiment with Air Pressure! Magdeburg Hemispheres: With two 4 3/4" diameter plastic half-spheres, handles, high quality pushbutton valve. 1/4" diameter pressure tubing. Withstands 180 lbs of force. Weight of Air Cylinder: 1000ml can with attached plastic valve and tubing. Vacuum Lifter: 10.5" diameter rubber disk with handle and rope. Force Pressure Cups: Soft rubber suctoins cups. Withstands 100 lb of force. Breaking Board Paradox: 10 thin slabs of wood that break with the proper force. Hand Vacuum Pump: Displaces 725 ml of air with 2-way pump. Plastic tubing, gauge in cm and inches Hg. Instructions tied into National Teaching standars and Benchmarks for Science Literacy with journal page.