The Milwaukee 13/32" Thunderbolt Black Oxide Drill Bit (48-89-2732) is highly recommended for portable drills for drilling through metal, wood, PVC, and even curved surfaces. The Thunderbolt web features a thicker core than standard drill bits, providing more strength and reducing side-load breakage. A specially designed parabolic flute form clears chips fast, while the 3-Flat Secure-Grip shank holds the bit firmly in the chuck.