Boa Quick Change Diamond Tip Drill Bits ith a vacuum brazed diamond tip, Boa Diamond Drills are developed for hard materials. This product has been 10 years in development with a welded diamond tip for greater strength and endurance. Manufactured in the UK, these drills will perform beyond expectation, and with the addition of the Boa CCV (Cool Clear Vision) guide and water cooling device this product stands out from the competition.