The Milwaukee® Shockwave™ 3-1/2" Phillips #1 Impact Duty™ Bit 2 Pack Is Engineered to Be The Most Durable, Best Fitting Driver Bits On The Market. The Phillips Bits Feature Wear Guard Tip™ For Increased Wear Resistance, Which Protects The Fit Over The Life Of The Bit. The Impact Driver Bits Have An Optimized Shockzone™ For Each Tip Type and Length Of Driver Bit to Absorb Peak Torque and Prevent Breaking. The Custom ALLOY76™ Steel Is Customized and Heat Treated Per Tip Type to Extend The Life Of The Driver