HHIP 4 Piece 1/4-1/2" double-end boring bar set is machined from selected steel for greater strength and rigidity. Includes the following: one 1/4 X 5" that takes a 5/32" round tool bit, one 5/16 X 5" that takes a 3/16" round tool bit, one 3/8 X 6" that takes a 3/16" round tool bit and one 1/2 X 6" that takes a 3/16" square tool bit. Broached holes accept high speed steel and carbide tool bits. Black oxide finish. Bars have one 45 degree end and one 90 degree end.