<b>Those spikes are magnetic field lines</b> <br><br> Most of us have performed (or seen pictures of) the classic magnetic field experiment. You place a bar magnet <br>underneath a piece of paper and then sprinkle iron filings on top. The filings arrange themselves in such <br>a way as to approximate the magnetic flux lines.<br> Using Ferrofluid in a Bottle, you can see this phenomenon in real-time and in 3D! The stronger the magnet, the <br>larger the spikes. And the closer the magnet is to the ferrofluid, the closer the spikes will be to each other. <br><br> <b>Two included magnets double the fun</b><br><br> Ferrofluid in a Bottle (60mL size) includes two small neodymium magnets which allow for some uber cool interactions.<br> You can bridge the fluid across the walls of the bottle as well as create a yo-yoing effect by moving the magnets back and forth.<br> Dimensions of bottle : 12*3cm<br> Number of Magnets : 2<br> Amount of Ferrofluid: 5ml inside <br> net weight: 116g<br> weight include package: 175g<br> package size : 20x8x5cm <br><br> <b>Package included</b><br> 1* Ferrofluid bottle<br> 1* Instructions<br> 2* Magnets<br> 2* Magnetic handles<br><br> <b>Warning: Keep away from children. Do not put magnets in mouth or nose. Swallowed magnets can stick to intestines<br> causing serious injury or death. Seek immediate medical attention if magnets are swallowed or inhaled. <br>Don't break the glass. When you're done, you can store the magnets on the top of the bottle cap.</b>