4 piece, forstner, high speed steel bit set, sharp center spur accurately locates the center of your hole, use for drilling flat bottom holes, pocket holes or overlapping holes, set includes 1 each: 1" (cut diameter: 1", overall length: 3-1/2", shank diameter: 3/8"), 3/4" (cut diameter: 3/4", overall length: 3-1/2", shank diameter: 3/8", 1/2" cut diameter: 1/2", overall length: 3-1/2", shank diameter: 5/16" & 1/4" cut diameter: 1/4", overall length: 3-1/2", shank diameter: 1/4".