About once a week somebody asks me where to buy the "M18™ air horn attachment" — like it's a chuck-in accessory hiding somewhere in the tool aisle. Let me clear this up, because I've tested these horns on my own trucks and side-by-sides for years: there is no attachment. What you saw in that video is a Train Horn for Milwaukee® 18v Battery — a standalone, self-contained horn that runs on the M18™ battery you already own. No drill involved, no wiring, no air tank.
The Short Answer: No Attachment Exists, and Nothing Chucks Into a Drill
Milwaukee® does not make an air horn, a train horn, or any horn attachment for the M18 platform. I've dug through the catalog myself, and I broke the whole question down in Does Milwaukee® Make a Train Horn? — short version: the horn products you see online are built by independent aftermarket companies, not by Milwaukee® Tool, and every legitimate seller says so right on the page.
Just as important: the horn is not something you clamp into a drill chuck or bolt onto a tool. Your drill stays in the toolbox. The product behind all those search results is a complete horn with its own housing, its own onboard air compressor, and its own metal trumpets. The only thing it shares with your power tools is the battery that slides onto the bottom.
What the "Air Horn for Drill" Actually Is
Here's the hardware, plain and simple. It's a handheld unit shaped roughly like a cordless tool: a pistol grip with a trigger, a compressor inside the body, and two to five powder-coated metal trumpets bolted on top. You click a Milwaukee® M18 pack onto the rail — same motion as loading your impact driver — pull the trigger, and the compressor drives air straight through the trumpets. No tank to fill, no relay to wire, no air lines to plumb. That's the entire install.
Because of the grip-and-trigger layout, a lot of people call this thing a "train horn gun" or "horn gun." If you've seen that nickname floating around, it's the same product — I explain where the name comes from in What Is a "Train Horn Gun"?
Why Everybody Calls It an "Attachment" (and Why That's Wrong)
I get why the word sticks. Three things trip people up:
- The battery interface. The horn accepts the exact same M18 slide-on pack as your tools, so it feels like part of the tool system. It isn't — it's an independent product that happens to run on that battery.
- The shape. Pistol grip, trigger, battery on the bottom. At a glance it reads "power tool accessory." Pick one up and the difference is obvious: it's a horn through and through.
- The search phrasing. Videos get captioned "air horn for drill" because the horn looks drill-style, and that phrasing snowballed. Nobody is attaching anything to a drill in those clips.
So if you've been hunting for an attachment SKU that fits your existing drill — stop. You don't need one, and one doesn't exist. You need the standalone horn, and you already own the expensive part: the battery.
How It Works: Battery, Compressor, Trumpets — Nothing Else
Traditional vehicle train horns need an air compressor, a storage tank, a relay, fuses, and a day of wiring. The battery-powered design skips all of it. The M18 pack powers the onboard compressor directly, and the compressor feeds the trumpets in real time — which is why the sound fires the instant you pull the trigger instead of waiting on tank pressure.
Loudness comes down to trumpet count and compressor output, and the lineup tiers out like this: dual-trumpet models start around 130 dB, quad-trumpet models push to roughly 140 dB, and the top tier crosses 150 dB. My pick of the range is the Extreme Quad Train Horn for Milwaukee® 18v Battery — the 150+ dB flagship I keep strapped in my own truck bed, with a wireless remote that reaches up to 2000 ft, so you can fire it from the cab, the house, or the far end of the lot.
Every model also fires from a wireless remote, not just the trigger. Standard remotes are rated to 160 ft; the long-range remote on the Extreme tier is the 2000 ft unit. Loud is a feature — install it right.
What to Check Before You Buy
If you're coming in from the "attachment" search, here's my honest checklist before you spend a dime:
- Battery fitment. Buy the version built for your packs. If your shelf is full of Milwaukee® M18 batteries, get an M18-compatible horn — the battery rail is platform-specific, and a horn built for another brand's pack won't click onto yours.
- Sound tier. 130 dB dual for the truck cab and tailgating, 140 dB quad for off-road and marine use, 150+ dB Extreme if you want the full locomotive effect. More trumpets, more volume.
- Remote range. 160 ft covers a driveway. If you want to trigger the horn from inside the house or across a job site, the 2000 ft long-range remote is the one to get.
- Assembled vs. kit. Pre-assembled horns work out of the box. If you like building your own gear, the DIY Quad Train Horn for Milwaukee® 18v Battery ships as components you put together yourself — same compressor and trumpets, lower price, a weekend-afternoon build.
FAQ
Can I turn my actual drill or impact driver into an air horn?
No. There's no chuck-in horn bit, no adapter, no conversion collar. The horn is its own complete device. Even the DIY kits are standalone builds — you're assembling a horn from horn parts, not modifying a tool. Your drill keeps its day job.
Does Milwaukee® sell any air horn or train horn at all?
No. These horns are independent aftermarket products that are compatible with Milwaukee® M18 batteries. Milwaukee® Tool doesn't manufacture, sell, or endorse them — the brand connection begins and ends at the battery.
Will running a horn hurt my M18™ batteries?
It draws power like any cordless tool — in short bursts, at that. Any M18 pack works, from a compact 2.0Ah up to a 12.0Ah. A bigger pack doesn't make the horn louder; it just gives you more blasts per charge. I've run packs to empty on test days and charged them right back up like normal.
Do I need hearing protection with one of these?
At close range, yes — treat it like a power tool for your ears. NIOSH recommends that peak impulse noise exposure not exceed 140 dB SPL, a threshold OSHA references in its noise-standard guidance. A 150 dB horn fired at arm's length is over that line, so I wear earplugs when I'm testing up close and I aim the trumpets away from people. Loud is the point; deaf is not.
— Cole
Milwaukee®, M18™, and other trademarks are the property of their respective owners. Our train horns are independent aftermarket products that run on Milwaukee® M18 batteries; they are not manufactured, sold, affiliated with, or endorsed by Milwaukee® Tool / Techtronic Industries. Trademarks are referenced solely to indicate battery compatibility.