Basically, its part core and part coverstock....
Yah yah.. i noe.. light weight means no core...
Its actually more to do with the pin placement and the reaction of its cover stock, spinner balls are generally expected to spin on its boottom and then filp slightly when it reaches the pins or the backend....
(so dun say spinner got nothing to consider about the oiling, cos if the lanes are too oily, spinner balls will go flat in the pocket and if too dry, ur ball will flip too early leaving little or no power at the end and u'll have to depend on pin action only.)
These balls are made in such a way that there is very little or no top weight on the ball, which allows it to spin smoothly and correctly, which those balls i mentioned are good at. Try using a light weight hook ball with 3oz top weight and see wat happens! Its will spin for the first half of the lane then when reaching the backend it;ll flip like crazy and end up rolling into the pocket!
Volia!! You are playing an 11lbs, weak sissy hook ball
. Meaning like people who top the ball alot... so far thats all i can think of, will update further if i can remember. Spinner actually have lots of techincal things too leh! just that it looks easier