Accurate size: The sleeve with accuracy and can accuratel for the screws, providing stable and tightening effects. Multiple specifications: This product includes four commonly used hexagonaled sockets,4.0mm, 5.5mm, 7.0mm, and 8.0mm, to meet different work requirements. Good from carbon steel with many characteristics Withstands torques, and providing long service life. Strong compatibility: suitable for various industry and field that require use of hexagonaled sockets, such as repair, furniture assembly, mechanical equipment maintenance, wide applicability.