4h1r1 Vaco hex power bit Klein tools  #1 x 1" square recess screwdriver replacement bit, this square recess screwdriver replacement bit meets or exceeds applicable ASME/ANSI specifications. These precision-milled bits are 1-Inch in length and are 1/4-Inch hex and fit replaceable-bit screwdrivers and other sockets that accept one quarter inch-hex bits.