Features and Benefits: S2 alloy steel bits for strength and durability; For use with pin type tamper resistant 5-Lobe fasteners; 1/4" and 3/8" drive bit holders; Handy magnetic holder sticks to most metal surfaces; 13-Piece Tamper Resistant 5-Lobe Bit Set16137 S2 alloy steel bits for strength and durability For use with pin type tamper resistant 5-Lobe fasteners 1/4 in. and 3/8 in. drive bit holders 11 bits, TP8, 10, 15, 20, 25, 27, 30, 40, 45, 50 and TP55 Handy magnetic holder sticks to most metal surfaces