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″.