The zipper is one of the simplest machines of modern times and arguably one of the least essential, but it is an immeasurably useful device in our everyday lives.
The slide brings the two rows of teeth together to ZIP closed and then pulls them away again when you UNZIP! Detail Description: A zipper track is made up of dozens of teeth, each of which combines a hook and a hollow. The idea is to latch every hook on each of the two tracks into a hollow on the opposite track.
