Made from S2 Tool Steel with proprietary heat treat for superior strength and durability, Mayhew insert bits have a precision tip profile for positive and precise fastener engagement. The size and durability of these hex bits make this set perfect for automotive, electronics, home improvement, and many other applications. This set includes 1/8", 9/64", 5/32", 3/16", 7/32", 1/4" in both standard and Tamper resistant hex. Included magnetic storage rail makes it easy to ensure these bits are always available when you need them.