These high speed steel forstner bits were designed for the precise cutting holes to show off prize coins, whether state quarters, president dollars or a custom set of your choosing. Each size has razor sharp spurs for perfect cuts. Due to expansion and contraction of wood, coins should be secured with double face tape. 6 pc.set includes penny, nickel, dime, quarter, half dollar and dollar sizes, collar and depth control. 3/8" round shanks.