The most popular yo-yo's these days have a ball bearing spindle instead of a fixed wood or metal post. Yo-yo's with a ball bearing spindle spin longer, sleep better and make it easier to perform complicated tricks. PSI spent nearly a year designing, testing, and perfecting this kit. The result is a yo-yo that works superbly and is easy to make. This project is made by turning the yo-yo sides on a 7mm pen mandrel using any style 10mm bushing setvStart with 5/8" thick wood for best results.