With inspiration of the Higgs Boson, but built from the ground up using a completely different shape. We at Phlebo have always been fans of urethane antirockers, so we decided to make our own, but out of 3d printable urethane. The material is very durable and more slick than the urethane found on your traditionally poured wheels. Durometer on these are rated at 95a, but they actually feel harder. All wheels come "ready to roll" with bearings and spacers preinstalled.