Clever idea: play and expand.

Video at Amazon.com view basis:
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Approximately 5-month-Maine Coone cat-BKH-mixing.
Very playful, creative and energetic.
The function of the toy can be seen in the video.

Pro:
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+++ Robust quality, rubberized feet to prevent slipping
+++ Structure: Rails plug together like puzzle - Fitting the cover and snap
+++ Ball rolls absolutely fluent
+++ Raised ends: ball rolls back and encouraged to continue playing
+++ Ball solid track: can not jump out or get lost
+++ Already varied as a starter - as a web, as a circle
+++ Expansion and changed by more rails

Cons:
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--- Takes relatively less storage space (except a circle), not necessarily for small apartments

Conclusion:
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Our kitten has accepted the toy excited. She takes you back to it. I would recommend this toy, even at this price (just under 13), clearly recommend.