Bought this on ebay, NOS in original package. It's called a Mock Motor, thinking 50's-60's. 98 cents new back in the day. Cheapo plastic toy. Stick the yellow piece into the hole on the back, clip it to the fender brace, and wake up the neighbors! Haven't mounted it to any bike yet. Just thought it was an unusual item, I like this sort of stuff. Anyone else have one? Thoughts?