Screwdriving bits made from premium S2 steel for long tool life while driving common or mild steel screws or case hardened screws. Fits multiple tip hand drivers and 1/4-Inch hex holders for power driving applications. Always use a bit holder for power driving applications. 7 Piece Set includes security star drive, T-10, T-15, T20, T-25, T-27, T-30 and magnetic bit holder.