The Titan Tools 16138 9-Piece Low Profile Impact Triple Square Bit Socket Set includes (2) 1/2-Inch drive, (3) 3/8-Inch drive, (4) 1/4-Inch drive bits, and steel storage rail. The sizes for 1/2-Inch drive bits are tamper resistant MT16 and MT18, sizes for 3/8-Inch drive bits are M10, M12, and tamper resistant MT14, and sizes for 1/4-Inch drive bits are M4, M5, M6, and M8. Bit sockets are impact grade. The low profile design for confined, hard to reach areas. Every low profile impact triple square bit socket set is made in Taiwan.