Attributes . Nut Driver Size No.: 5/16 in , 1/4 in ; Phillips Bits: Size No. 1, 2 ; Slotted Bits: 1/4 in (6.4 mm), 3/16 in (4.8 mm) ; Square Bits: Size No. 1, Size No. 2 ; TORX Bits: T10, T15 . Names