Quote:
Originally Posted by chain-addicted
What's a "zipper top"? 
Someone fill me in on this please. |
Zipper top/bottom/wing discs have tiny little concentric grooves running along them, and they make a "zipper noise", like a vinyl record, if you run your finger nail along them. Usually this just means that the mold piece is so new that the little machining imperfections haven't been smoothed out yet.