The whole point of a battery-powered train horn gun is that it runs off a battery you already own. But here's the catch most buyers miss: power-tool batteries are not universal. The pack that fits your Milwaukee drill will not slide onto a DeWalt tool, and the same rule applies to horn guns. This chart sorts out exactly which power-tool brand fits which horn gun, why the platforms don't mix, and what to do if your brand isn't on the list.
First, the 18V vs 20V MAX confusion
Before you read a single spec, clear up the number that trips everyone up. A "20V MAX" battery and an "18V" battery are the same thing electrically. The 20V figure is the peak, no-load voltage measured the instant you pull a fresh pack off the charger; the 18V figure is the nominal (working) voltage that pack actually delivers under load. Every one of these packs is built from five lithium-ion cells wired in series, and each cell sits around 3.6V nominal (about 4.0V at full charge). Five times 3.6 is 18; five times 4.0 is 20. Same battery, two different marketing labels.
So why do brands disagree? It's purely a naming choice. In the US, Milwaukee (M18), Makita (LXT), Ryobi (ONE+), Bosch, and Ridgid all advertise the nominal 18V. DeWalt, Craftsman, Bauer, Hercules, and Hart advertise the 20V MAX peak. None of that changes how loud your horn gets or how long it runs — it's the same 18V working voltage feeding the air pump either way.
The battery compatibility chart
Here's the part you came for. Find your battery brand in the left column, and the right column tells you which horn gun is built to accept that exact pack. Every horn gun uses the genuine brand battery interface, so your existing packs and chargers just work — no adapters, no rewiring.
| Battery brand | Platform name | Label on the pack | Matching horn gun |
|---|---|---|---|
| Milwaukee | M18 | 18V | 5-Trumpet & Quad / Dual horn guns |
| DeWalt | 20V MAX | 20V | 5-Trumpet, Quad & Dual horn guns |
| Makita | LXT | 18V | Quad & Dual horn guns |
| Ryobi | ONE+ | 18V | Quad & Dual horn guns |
| Bosch | 18V | 18V | Quad & Dual horn guns |
| Ridgid | 18V | 18V | Quad & Dual horn guns |
| Craftsman | V20 | 20V | Quad & Dual horn guns |
| Bauer | 20V (Harbor Freight) | 20V | Quad & Dual horn guns |
| Hart | 20V (Walmart) | 20V | Quad horn gun |
| Hercules | 20V (Harbor Freight) | 20V | Quad horn gun |
If you run on the Milwaukee M18 system, the flagship is the 5-Trumpet Horn Gun for Milwaukee® 18V Battery — five trumpets fed by the same M18 pack that powers your drill or impact driver.
Every other brand has a matching model built around its native battery foot, so you can pick the trumpet count you want on the platform you already own.
Why you can't just swap batteries between brands
This is the question we get most: "Can I use my DeWalt pack on the Ryobi horn?" The answer is no, and it's not an artificial limitation we added — it's baked into how the tool industry works. Each manufacturer designs a proprietary battery interface: a unique set of rails, locking tabs, and terminal positions that physically only mate with that brand's tools. A Milwaukee pack won't slide onto a Makita foot any more than it would slide onto a DeWalt drill.
It goes deeper than the physical shape. Modern lithium packs talk to the tool through a battery management system (BMS) — the electronics that monitor cell temperature, prevent over-discharge, and regulate current flow. Those communication protocols are specific to each brand. That's why even brands owned by the same parent company don't interchange: Ryobi, Milwaukee, Ridgid, and Hart are all under the same corporate umbrella (TTI), and Bauer and Hercules are both Harbor Freight brands, yet each keeps its own exclusive pack design. So when you order a horn gun, you order it for one specific battery platform. Match it to the batteries already sitting in your garage and you're done.
What if my brand isn't on the chart?
The chart above covers the ten most common platforms, but the cordless world is bigger than that — Kobalt, Flex, Porter-Cable, Skil, and Black+Decker all have their own packs too. If you run one of those, or you simply want the freedom to wire in whatever battery you've got, the universal DIY route is the answer. A DIY kit ships with the air horn assembly and trumpets and lets you connect your own power source, so you're not locked to one brand foot.
A quick gut-check before you buy: pull a battery off your most-used tool, read the brand and the voltage printed on the label (18V or 20V MAX — remember, both are fine), and match that to the chart. If the brand is listed, grab the dedicated horn gun. If it isn't, go DIY.
How battery choice affects runtime and loudness
Since every platform delivers the same 18V working voltage, your horn's volume doesn't change from brand to brand — an air horn gun pushes the same air pressure whether a Milwaukee or a Craftsman pack is feeding it. What does change is how long you can keep blasting between charges, and that comes down to amp-hours (Ah), not the brand badge. A 5.0Ah pack simply stores more energy than a 2.0Ah pack on the same platform, so it runs longer. Since a horn only draws power in short bursts, even a modest 2.0Ah battery is good for a long day of use. If you already own higher-capacity packs for heavy tools, those will give you the most run time on the horn too.
FAQ
Are 18V and 20V MAX horn guns different products?
Electrically, no — both run at 18V nominal. The difference is only the physical battery foot and which brand's label says what. A horn gun built for DeWalt (20V MAX) and one built for Milwaukee (18V) deliver the same air output; they just accept different packs.
Do I need an adapter to use my batteries?
No. Each horn gun is built with the genuine battery interface for its platform, so your existing packs click straight on. Third-party adapters exist for tools, but you don't need one here as long as you order the horn gun made for your brand.
Can one horn gun work with two battery brands?
Not directly — the physical foot fits one platform. If you own tools across two brands and want flexibility, the universal DIY kit is the way to cover both with one horn.
Will a bigger battery make the horn louder?
No. Loudness is set by the horn and air pump, both fed at a constant 18V. A higher amp-hour battery extends run time, not volume.
My brand uses a 20V MAX label — is that too much voltage for the horn?
Not at all. 20V MAX is just the peak reading of a standard 18V pack. Horn guns for DeWalt, Craftsman, Bauer, Hercules, and Hart are designed for exactly that pack, so there's no mismatch.