3/8" Thunderbolt® Black Oxide Drill Bit (6 PK)

The Milwaukee 48-89-2840 is a 3/8" Thunderbolt® black oxide jobber-length drill bit set (6-pack) designed for general-purpose drilling in metal, wood, and plastic.

This is one of Milwaukee’s standard Thunderbolt twist drill bits, meaning it’s focused on everyday drilling performance and durability, not oversized or long-reach applications like the S&D or aircraft-length bits you were looking at earlier.

Key Features

• 135° split point tip – starts on contact and helps prevent walking for accurate holes
• Black oxide coating – reduces friction and improves corrosion resistance
• Parabolic flute design – clears chips quickly for faster, cooler drilling
• Thicker reinforced web (Thunderbolt design) – improves strength and reduces breakage under load
• 3-flat Secure-Grip shank – prevents slipping in the drill chuck

Specs

• Size: 3/8 in
• Quantity: 6 bits per pack
• Material: High-speed steel (HSS)
• Finish: Black oxide
• Length: ~5 in jobber length
• Use: Metal, wood, PVC, plastics

Best Uses

• General construction drilling
• Light steel and metal fabrication
• Wood framing and shop work
• Maintenance and repair drilling
• Everyday jobsite drilling where durability matters

Bottom Line

The 48-89-2840 is a basic heavy-duty 3/8" drill bit set—not specialty or oversized. It sits in the “workhorse” category of Milwaukee bits: durable, common size, and meant for repeated general use across most materials.