Lutz 23048 1/4 Magnetic Bit Holder with Lock. All Lutz High-Performance Bits go through a rigorous development process to ensure that they are top quality and will last, no matter the circumstances. Lutz Bits are made of chrome vanadium 6150 steel alloy, which is heat treated to a Rockwell of 58 to 60. After strength and durability is tested, the bits are coated with an oil mist for rust resistance.