Milwaukee SDS-Plus 4ct MX4 5 PC Kit

Milwaukee’s MX4 kit solves the most expensive problem in concrete drilling — bits that die the moment they hit rebar. The 4-cutter design delivers up to 5x longer life when drilling through rebar-reinforced concrete compared to standard bits. At 4.8 stars across 296 reviews, contractors have spoken.

Skip it if you’re drilling clean concrete without rebar. Standard 2-cutter bits cost less and work fine in unreinforced material. But for industrial work, bridge construction, or any project where rebar is guaranteed, the MX4 earns its premium.

The Rebar Problem Solved

The 4-cutter design prevents lock-up in rebar, reducing downtime — that’s the core innovation. Traditional 2-cutter bits bind when they hit steel, forcing you to back out, reposition, and try again. Sometimes they snap. Always they overheat.

Milwaukee’s MX4 uses solid head carbide construction with rebar guards for maximum durability in hard aggregate and rebar. The geometry matters. Four cutting edges distribute the impact load, preventing the catastrophic binding that kills standard bits.

Up to five times longer than standard bits—especially when drilling through rebar and hard aggregate. That’s not marketing fluff. When you’re billing by the hole or racing a concrete pour, bit life translates directly to profit.

Battery Runtime That Matters

Cordless rotary hammers changed the game for overhead work and remote jobsites. The MX4 design acknowledges this shift with features that maximize runtime.

Variable flutes for faster drilling/dust removal and more holes per battery charge deliver measurable efficiency. Up to 20% more holes per battery charge compared to other 4-cutter bits. The variable flute geometry clears debris faster, reducing friction and heat buildup.

Less heat means less battery drain. The motor doesn’t work as hard to maintain speed when the bit runs cooler. Simple physics that shows up in real-world runtime.

Kit Contents and Compliance

Size	Quantity	Application
3/16” x 6”	1	Small anchors, pilot holes
1/4” x 6”	2	Most common anchor size
5/16” x 6”	1	Medium anchors
3/8” x 6”	1	Larger mechanical anchors

They meet ANSI B212.15 standards for compatibility with common anchors and have a wear mark indicator to signal when the bits no longer meet performance requirements. That wear mark matters for inspection jobs. You can prove your bits meet spec without measuring.

The sharp centering tip for exact spot drilling in concrete and metal decking addresses a specific pain point. Metal decking deflects under a standard bit’s blunt nose. The MX4’s sharp tip bites immediately, maintaining position even on painted or galvanized surfaces.

The Verdict

Worth the money for crews drilling rebar-reinforced concrete daily. The durability claims check out — five times longer than standard bits in the worst conditions. Add the battery efficiency gains and precise starting, and you’ve got bits that earn their keep.

The kit configuration makes sense. Two 1/4” bits because that’s what you’ll burn through. One each of the other sizes for versatility. Fully compatible with all SDS-Plus rotary hammers, so brand loyalty isn’t required.

Not revolutionary. Just properly engineered bits that acknowledge what actually destroys them — rebar strikes and heat buildup. Milwaukee built these for contractors who track cost per hole, not homeowners hanging pictures.

Frequently Asked Questions

What makes the MX4 different from standard SDS-Plus bits?

The 4-cutter design prevents lock-up in rebar, while standard 2-cutter bits bind and overheat when they hit steel. Solid head carbide construction and rebar guards provide the durability difference. The result is up to five times longer lifespan when drilling through rebar and hard aggregate.

Do these bits really deliver 20% more holes per battery charge?

Up to 20% more holes per battery charge comes from the variable flutes for faster drilling/dust removal. Less friction means less heat, which means your motor draws less current. The improvement shows up most in deep holes where debris removal becomes the limiting factor.

What’s included in the 5-piece kit?

1 x 3/16” x 6” SDS-PLUS 4-Cutter MX4 Bit, 2 x 1/4” x 6” SDS-PLUS 4-Cutter MX4 Bits, 1 x 5/16” x 6” SDS-PLUS 4-Cutter MX4 Bit, 1 x 3/8” x 6” SDS-PLUS 4-Cutter MX4 Bit. All bits are 6 inches long and work with any SDS-Plus rotary hammer.

When should these bits be replaced?

A wear mark indicator signals when the bits no longer meet performance requirements. This visible indicator ensures ANSI B212.15 compliance without guesswork. When the wear mark disappears, the bit no longer meets anchor manufacturer specifications.

Are these bits worth it for occasional use?

Not really. Some potential weaknesses noted by users include the higher cost compared to other bit sets and possible over-specification for lighter tasks. The set is primarily intended for professional use, so it might be less economical for occasional or light-duty projects. Save your money if you’re drilling a few holes in a basement wall.