Bill Soukes from New Mexico
The item was as expected and it was shipped promptly.
Rattleback - Multicolor Pack of 10
Bob from Augusta, GA
Great product, have used to give out to clients for years. Bought an engraver this time and added my logo too! Great for kids and adults. Service excellent!!!
just plain fun
Jack from ILL
I had one as a child and I wanted to pick some up for the "kids" I work with, I am passed 60
The Old Man from Bloomington, IL USA
I handed these out to a younger generation and most even put down their smart gizmos to pay attention and learn. For a while I went from old man to a rock star.
Allan S from Houghton, MI
BV from Texas, USA
Great. Very fast, very professional, excellent service and very fair price. I use them as inquiry objects and advertising ideas.
Linda Dettling from Boulder, Co. USA
The package of multi-colored Rattlebacks arrived shortly after my order
was placed. I love giving them to kids and friends because they are so
Great scientific toy
George Streit from La Verne, California
I have been forever fascinated by these little things. I had one when I was a kid , made of wood. I've given away over 100 of them to friends or strangers, just to see their reaction to the strange toy that wants to spin in only one direction........
John Young from Pittsburgh, PA USA
Rattlebacks defy the laws of physics. A person can't have too many. Great to pass out to grandchildren.
Kids love these!
Great Scientific Toy
George Streit from La Verne. Ca
I carry these toys in my pocket and give them away to children or people i like. They are great for getting people to think about why they do what they do.
Mark from San Angelo, Texas
Came on time and very pleased with the price and product.
Celt or Rattleback
Douglas from California
What a truly fascinating object. The CELT (or rattleback) is a semi-ellipsoidal object which will spin on its axis in a preferred direction. Place it on a flat surface and spin it in a counterclockwise direction. As one might predict, it will spin, slowing down as the frictional force acting on the Celt from the supporting surface eventually brings it to a stop. Now, spin it in a clockwise direction and observe. It becomes unstable, yaws back and forth, stops then reverses its spin to counterclockwise.
This spin-reversal motion seems to violate Newton's angular-momentum conservation law of physics which is, stated simply, objects in motion remain in motion until acted upon by an external force. Most Celts exhibit this phenomenon when spun in one direction, but not when spun in the other. Some exceptional Celts will reverse when spun in either direction. This makes the Celt a physical curiosity that has perplexed human imagination since prehistorical times. These are made of plastic, but stone and wood Celts have been found at ancient archeological digs sites (so I have read).
Professional Civil Engineer
Saved Big buying the 10 pack
Mike Daily from Newtown, PA
Ok so I only wanted one of these, after seeing it on Youtube. Most websites have them listed somewhere between $2 - $5 each. Which isn't too bad, but with shippping it's between $7 - $10 for ONE plastic rattleback! Needless to say I kept searching. I found this 10 pack which brought the cost down to .89 cents each. Add the shipping and it came to $14 total for 10. You do the math. 1 for $10, or 10 for $14? I kept a few of different colors and gave the rest to my nieces and nephew.