- +Honest, realistic 128 dB rating instead of inflated marketing numbers
- +Low-range 308/337/366 Hz tuning sounds deeper than most compact kits
- +Flat-rack trumpet layout needs less mounting depth than fan-style horns
- +Light reinforced-ABS build is easy on brackets and mounting points
- +Built-in 12V/300 mA solenoid plus 10 ft of hose included
- +In stock direct from Wolo at $159.99
- −Horn only — compressor and tank must be bought separately
- −Wolo does not disclose the dB test distance
- −ABS trumpets can't match the tone or durability of metal horns
- −No warranty terms published on the product page
- −Matching 855-858 Express Pro combo was out of stock at review time
Methodology
This review aggregates publicly available information from manufacturer specifications, retailer listings, and verified user reviews. We do not perform hands-on testing. Last reviewed: July 31, 2026. Our sources for this article are Wolo’s official product pages for the Model 855 and its Express Pro combo kits, and a retailer’s YouTube sound demo — all linked in the Sources section at the end.
Quick verdict
The Wolo 855 Wolo Express earns a 3.7/5 from us. It’s a three-trumpet, horn-only train horn with an unusually honest 128 dB rating, a genuinely low 308/337/366 Hz chord, and a flat-rack design that solves the number-one packaging headache of under-truck installs. What holds it back is the same thing that holds back every horn-only product: by the time you add the compressor and tank it actually needs, the real cost lands closer to $275–$300. If you already have onboard air, though, this is one of the easier recommendations in Wolo’s train horn line.
What it is
The Model 855 Wolo Express is the entry point of Wolo’s Express family of train horns. It’s a horn-only product: three black trumpets molded from reinforced ABS plastic on an enamel-painted base, with a built-in 12-volt electric solenoid valve. There is no compressor and no tank in the box — Wolo explicitly states the horn requires an onboard air system and recommends its own Model 840, 858, or 860 compressor systems to drive it.
Wolo says it was the first company to design and sell ABS train horns, and the 855 leans into that heritage. The trumpets sit side by side on a universal flat rack rather than stacked in the fan arrangement most chrome train horns use, so the whole assembly needs less vertical clearance — the kind of detail that matters when you’re hunting for space between a frame rail and a truck bed. Per Wolo’s spec sheet, the assembly measures 19 in. long by 18 in. wide by 9.5 in. high.
The target buyer is a pickup, SUV, or light-truck owner who wants real train-horn tone without locomotive-horn money — and who either already has an air source or is prepared to buy one.
On sound character: a YouTube demo of the Model 855 published by retailer Northern Tool shows a blended three-note blast that reads as a single deep chord rather than three separate tones, with the low-range tuning doing most of the work. That 308/337/366 Hz spread sits noticeably lower than the 400–500 Hz territory of typical dual-trumpet air horns, which is what pushes the 855 toward “train” rather than “big rig” in character — our trumpet tuning guide explains why lower, tighter chords sound bigger than their decibel number suggests.
Specifications
| Spec | Value |
|---|---|
| Sound output | 128 dB (test distance not disclosed) |
| Operating pressure | 90–110 PSI |
| Trumpets | 3, reinforced ABS plastic, semi-gloss black |
| Chord | 308 / 337 / 366 Hz (low range) |
| Base | Steel rack, painted enamel |
| Dimensions | 19 in. L × 18 in. W × 9.5 in. H |
| Valve | Built-in 12V electric solenoid, 300 mA |
| Air line | 10 ft of 1/4 in. O.D. high-pressure hose included |
| Fittings | Brass |
| Air source | Not included — onboard air required (Wolo 840 / 858 / 860 recommended) |
| Price (Wolo direct) | $159.99 |
A note on that decibel number: 128 dB is far below the “150 dB” claims plastered across budget train horn listings, and that’s a point in Wolo’s favor, not against it. Wolo publishes the rating alongside its 90–110 PSI test pressure, and as we explain in our guide to advertised vs real-world decibels, realistic manufacturer numbers in the high-120s routinely out-honk “150 dB” specials in real-world comparisons. Wolo does not, however, state the distance at which 128 dB was measured — a disclosure we’d like to see.
What it includes
- Three-trumpet ABS horn assembly on flat mounting rack
- Built-in heavy-duty 12-volt electric solenoid valve
- 10 ft of 1/4 in. O.D. nylon high-pressure hose
- Brass air fittings
- Mounting hardware
- Installation manual (also downloadable from Wolo’s site)
What it does not include is everything on the air side: no compressor, no tank, no pressure switch. Wolo’s recommended pairing is its Model 840 compressor or the more complete Model 858 / 860 air systems.
Pros
- Honest 128 dB rating with published 90–110 PSI test pressure — no inflated marketing numbers
- Genuinely low 308/337/366 Hz chord; deeper voice than most compact air horns
- Flat-rack layout needs less mounting depth than fan-style trumpet clusters
- Lightweight reinforced-ABS construction is easy on brackets and won’t rust
- Solenoid, hose, fittings, and hardware are all in the box — only air is missing
- In stock direct from Wolo at $159.99 with a published install manual
Cons
- Horn-only: Wolo’s factory combo kits put the true all-in cost at $273.99–$298.99
- dB test distance not disclosed, so cross-brand comparisons are approximate
- ABS trumpets don’t deliver the tone, weight, or longevity of metal horns
- No warranty terms published on the product page
- The matching 855-858 Express Pro combo was listed out of stock at Wolo at review time
Alternatives
- Wolo 853 Philly Express — the 855’s smaller sibling; a more compact ABS train horn for tighter installs. See our Wolo 853 Philly Express review.
- Wolo Quadraphonic Express PRO 877-858 — Wolo’s four-trumpet flagship combo rated 153 dB, with the 858 air system bundled in; roughly triple the price. See our Quadraphonic Express PRO review.
- Vixen Horns VXH3318B — a three-trumpet metal alternative in the same general price tier once you factor in air. See our Vixen VXH3318B review.
Install / compatibility notes
The 855 needs a 12-volt vehicle and an onboard air supply capable of 90–110 PSI. If you don’t already run air, you have two Wolo-sanctioned paths:
- Buy the horn plus a compressor system separately. Wolo recommends its Model 840, 858, or 860. The 858 pairs a 21-amp, 2.55 CFM oil-less compressor with a 2.5-gallon tank.
- Buy a factory combo. Wolo sells the same horn bundled as the 855-858 Express Pro ($273.99 at Wolo) and the larger 855-860 Express Pro Plus. The Pro combo was out of stock at Wolo when we last checked.
Electrical demands are light: the built-in solenoid draws just 300 mA, so the horn circuit itself needs only a simple switched 12V feed — the compressor is what needs relay-and-fuse planning (see our amp draw and wire gauge guide). The 10-foot length of 1/4-inch hose in the box sets a practical limit on how far the horn can sit from the tank; longer runs or a bigger line are an easy upgrade, as covered in our air line size guide.
One planning note on air consumption: at 90–110 PSI, a three-trumpet horn drains a small tank quickly, so honk length depends heavily on which air system you pair. The 858’s 2.5-gallon tank is the sensible floor for repeated full-length blasts; the compressor’s 2.55 CFM rating then dictates how fast you’re back to full pressure between honks. Our air tank size guide walks through the math.
At 19 by 18 inches, the rack wants a flat, sheltered spot — under-bed rails and behind-bumper locations are typical. Our mounting location guide covers spray protection and trumpet angling; ABS tolerates weather well, but facing the bells downward or rearward keeps water out of the diaphragms. Before install, check your local rules in our state horn law index — modified-horn enforcement varies widely.
Sources
- Wolo — Model 855 Wolo Express product page — price ($159.99), 128 dB rating, 308/337/366 Hz chord, 90/110 PSI test pressure, dimensions, ABS construction, 12V/300 mA solenoid, included hose/fittings/hardware, recommended 840/858/860 compressors, stock status
- Wolo — Model 855-858 Express Pro combo page — combo price ($273.99), 858 air system specs (21A, 2.55 CFM, 2.5-gallon tank, 20 ft filler hose), out-of-stock status
- Wolo — Model 855-860 Express Pro Plus combo page — existence, naming, and $298.99 price of the larger factory combo
- Wolo — Model 877-858 Quadraphonic Express PRO combo page — 153 dB rating, four metal trumpets, bundled air system, and pricing behind the alternatives comparison
- YouTube — Wolo Express Train Horn 3 Trumpets Model 855 (Northern Tool demo) — retailer sound demonstration of the 855’s chord
Train Horn Hub aggregates publicly available data. We do not test products in-house. All trademarks belong to their respective owners.
The 855 Wolo Express is a sensible pick for truck owners who already run onboard air and want a deep, honestly rated 128 dB triple horn in a compact flat-rack footprint — but buyers starting from zero should price the full combo kits before committing.
Frequently asked questions
Quick answers to the questions people ask most about this topic.
- How loud is the Wolo 855 Wolo Express really?
- Wolo rates the 855 at 128 dB at its 90–110 PSI operating pressure, without disclosing the test distance. That's a realistic manufacturer number — honest ratings in the high-120s typically sound as loud or louder in practice than budget horns advertising 150 dB.
- Does the Wolo 855 come with a compressor?
- No. The 855 is horn-only: you get the three-trumpet assembly, built-in 12V solenoid, 10 ft of 1/4-inch hose, fittings, and hardware. Wolo recommends pairing it with its Model 840, 858, or 860 onboard air systems, or buying the pre-bundled 855-858 Express Pro or 855-860 Express Pro Plus combos.
- What does the Wolo 855 cost all-in?
- The horn alone is $159.99 direct from Wolo. The factory 855-858 Express Pro combo with compressor and 2.5-gallon tank lists at $273.99 at Wolo, which is a realistic all-in figure if you're starting without onboard air.
- Are the ABS plastic trumpets a downgrade from metal?
- They're a trade-off. Reinforced ABS is lighter, rust-proof, and cheaper than chrome-plated metal, and Wolo pioneered ABS train horns. Editorially, metal trumpets tend to hold up better long-term and many buyers prefer their tone, but the 855's low 308/337/366 Hz tuning still delivers a convincingly deep chord.
- How much space does the Wolo 855 need?
- The flat-rack assembly measures 19 inches long by 18 inches wide by 9.5 inches high. The side-by-side trumpet layout needs less vertical clearance than stacked fan-style horns, which is why under-bed and behind-bumper mounts are the typical locations.
