Description
You display two different colored strings which pass through two plastic blocks.
You can pull either string to show that it passes through both blocks.
For example. The yellow string is at the top and the red string below. Now pull the blocks apart completely and the yellow string is at the bottom and red string on top!
Slide the blocks up and down and the colored strings keep changing places!
The effect is easy-to-do and is self-working. You can repeat as often as you like.




