DURABLE: This 10 piece female Torx socket set is made from chrome vanadium steel for durability. CONTENTS: The set includes 5 x 6mm (1/4") square drives (E4, E5, E6, E7, E8) and 5 x 9.5mm (3/8") square drives (E10, E12, E14, E16, E18) with a storage rail.