Zircon blocks are the most efficient small boat blocks Harken has ever made. At the core of Zircon performance are industrial ceramic ball bearings mounted inside caged races. The cages keep these bearings apart so they don’t bunch up, touch, and stop each other. The result is a very free-running block with less energy lost to friction than in even the current Carbo blocks. Give an unrigged Zircon block a strong spin, and it spins for an incredibly long time. Zircon bearings are more than 700% stronger in compression than stainless bearings of the same size. So, they won’t deform if used within the recommended load limits. More importantly, they don’t absorb as much energy before starting to roll. This becomes evident when you need to ease a sail in very light air. You feel even the slightest fluctuations in sheet load. When used expertly, that means better sail shape and more speed.