Diablo Forstner bit set includes the following bits: 1/4", 1/2", 3/4" and 1". Forstner bit, Diablo series, high speed steel, drill clean holes in wood & most wood products, sharp center spur accurately locates the center of your hole, use for drilling flat bottom holes, pocket holes or overlapping holes, specifications: cut diameter: 1-3/8 In., overall length: 3-1/2 In., shank diameter: 3/8 In..