The Irwin Torx insert screwdriver bits are engineered for use in hand-driving applications or with power tools. They are designed for use in an insert holder with C-clip for retaining ring notch. They are compact and versatile with a 1/4 inch hex body and made from high grade S2 steel. The Irwin Screwdriver Torx bits come in a pack of 10 with the following dimensions: T40 x 25mm. IRWIN Screwdriver Bits Torx Tx40 X 25Mm Pack Of 10 in Silver