It looks like a toy but it is not. This YoYoFactory Hubstack Afterglow...
You can now replace the string on your Yo-Yo. All you need is this pac of 5 polyester Duncan strings.
A good Yo-Yo string is essential for getting the most out of playing. Pack with 5 Yo-Yo Strings of Duncan made of 50% Cotton / 50% Polyester.