- +Complete kit: horn, 12V compressor, 2.5-gal tank, solenoid, hoses, hardware
- +Bright chrome-plated trumpets — the premium finish in the Siberian line
- +Authentic low-range 307/347/440 Hz three-note chord
- +Unusually detailed published specs (duty cycle, CFM, pressure-switch points)
- +Tank includes gauge, relief valve, and manual water drain
- +2.5-gallon tank supports long, repeated blasts at this price point
- −152 dB rating lacks a disclosed test distance
- −Wolo's own page copy contradicts the spec table (ABS text vs all-metal spec)
- −No warranty terms published on the product page
- −Out of stock at Wolo direct at review time
- −33% compressor duty cycle means cool-down pauses on long refills
- −Chrome finish needs upkeep in salt-belt winters
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: August 26, 2026. Primary source: Wolo Manufacturing’s official product page for the Model 850-858, cross-referenced against retailer listings at Summit Racing, Amazon, XDP, and Zoro, plus Wolo’s own YouTube demo of the Siberian Express Chrome series.
Quick verdict
The Wolo 850-858 Siberian Express Chrome PRO is one of the most complete mid-priced train horn packages you can buy: a chrome-plated triple-trumpet horn bundled with a genuinely full onboard air system — 12-volt compressor, 2.5-gallon metal tank, solenoid, hoses, and hardware — for a $389.99 list price. Wolo publishes unusually detailed specs (chord frequencies, duty cycle, CFM, even the pressure-switch cut-in/cut-out points), which we always reward. It loses points for not disclosing the dB test distance, for a warranty that isn’t stated on the product page, and for spotty availability at the moment. We rate it 4.1/5 — a strong value pick if you can find it in stock.
What it is
The 850-858 is a bundle: Wolo’s Model 850 Siberian Express Chrome triple-trumpet train horn packaged with the Model 858 high-pressure onboard air system. The horn plays a three-note low-range chord at 307/347/440 Hz and is rated at 152 dB with 90–110 PSI behind it (Wolo does not state the measurement distance). The trumpets wear a bright chrome-plated finish and the mounting base is painted enamel — this is the showpiece version of the Siberian Express family, next to the black-trumpet Wolo 847 and the closely related 852 chrome variant.
One honest caveat from our research: Wolo’s own description paragraph on the 850-858 page says the horn is “engineered with the latest technology using reinforced ABS plastic,” while the specification table on the same page lists the horn construction as all-metal. Wolo publishes the same all-metal spec line on the ABS-trumpet 852’s page, so the table doesn’t settle it — we treat the chrome finish as confirmed and the underlying trumpet material as unconfirmed. It’s a discrepancy worth knowing about before you buy.
Who it’s for: pickup and semi owners who want an authentic, deep three-chime train horn sound with everything needed in one box, and who care how the horn looks — on a show truck or a chrome-heavy rig, the plated trumpets are the point.
How it sounds
In Wolo’s official demo video of the chrome Siberian Express series, the horn delivers a broad, layered blast rather than a single shrill tone — the 307/347/440 Hz trio sits low enough to read as “train” instead of “air horn,” which is exactly what buyers in this class are paying for. Editorially, we’d describe the recorded character as rounder and slightly softer-edged than the locomotive horns we cover, but far deeper than higher-pitched compact quad kits. As always with compressed video audio, treat any demo as a rough guide to timbre, not loudness.
Specifications
| Spec | Value |
|---|---|
| Sound output | 152 dB at 90/110 PSI (test distance not disclosed) |
| Trumpets | 3, low-range chord |
| Frequencies | 307 / 347 / 440 Hz |
| Construction | Chrome-plated trumpets; base painted enamel |
| Horn dimensions | L 16.5” × W 14.75” × H 11” |
| Solenoid valve | 12 V / 250 mA electric solenoid |
| Compressor | 12 V, 21 A peak, 33% duty cycle @ 100 PSI, 2.55 CFM |
| Compressor motor | Gearless permanent-magnet, thermal protection |
| Compressor dimensions | L 10.25” × W 3.5” × H 6.5” |
| Air tank | 2.5-gallon metal, pressure switch on 80 / off 110 PSI |
| Tank dimensions | L 17.25” × W 6.5” × H 8.25” |
| Tank features | Pressure gauge, relief valve, manual water drain, brass fittings |
| Hoses | 10 ft flexible 1/4” OD high-pressure hose + 20 ft coiled filler hose |
| Kit weight | 33 lbs |
| Power source | Onboard air (12 V compressor + tank, included) |
| List price | $389.99 (Wolo direct; out of stock at time of review) |
| Warranty | Not stated on the product page |
What’s in the box
- Siberian Express Chrome triple-trumpet horn (Model 850)
- 12-volt onboard air compressor, 2.55 CFM, gearless permanent-magnet motor
- 2.5-gallon metal air tank with built-in pressure switch (80 on / 110 off), gauge, relief valve, and manual water drain
- 12-volt / 250 mA electric solenoid valve
- 10 ft of flexible 1/4” OD high-pressure hose
- 20 ft coiled filler hose
- Mounting hardware and brass fittings
Pros
- Truly complete kit — horn, compressor, 2.5-gallon tank, solenoid, hoses, and hardware in one box at a mid-tier price
- Bright chrome-plated trumpets — the premium finish in the Siberian Express line, versus the semi-gloss-black 847
- Authentic low-range 307/347/440 Hz three-note chord, closer to a real locomotive voice than high-pitched budget triples
- Unusually complete published specs: chord frequencies, duty cycle, CFM, pressure-switch set points, and dimensions for every component
- Tank ships with real instrumentation — gauge, relief valve, and a manual water drain, which cheap kits often omit
- 2.5 gallons of stored air supports long, repeated blasts between compressor refills
Cons
- 152 dB rating has no disclosed test distance, so it can’t be compared directly against honestly measured horns
- Wolo’s own product description contradicts its spec table (“reinforced ABS” copy vs. all-metal spec), leaving the trumpet material ambiguous — sloppy for a flagship page
- No warranty terms published on the product page
- Out of stock at Wolo direct at review time — check current availability before planning an install
- 33% duty cycle at 100 PSI means the compressor needs cool-down time after refilling the big tank
- Chrome plating on a frame- or bumper-mounted horn needs regular care in salt-belt winters
Alternatives
- Wolo 847 Siberian Express — the same 152 dB, 307/347/440 Hz triple in black-finish form as a standalone horn; the budget path if you already own an air source.
- Wolo 870-858 Western Express PRO — Wolo’s other PRO-series bundle built on the same 858 air system, with the Western Express horn’s different look and voice.
- HornBlasters Conductor’s Special 228H — the step-up option: a Shocker-based kit with a stronger support ecosystem, at a notably higher price.
Browse all our Wolo reviews for the rest of the Siberian and Express family.
Install / compatibility notes
This is a full onboard-air install, not a plug-and-play swap. Plan for:
- Space. The horn needs roughly a 16.5” × 14.75” footprint with 11” of height, the tank runs 17.25” long, and the compressor adds another 10.25” — under-bed or frame-rail mounting on a full-size pickup is typical. Our tank sizing guide covers placement trade-offs.
- Electrical. The compressor pulls up to 21 A at peak, so it should be wired through a relay and fuse directly to the battery. The 250 mA solenoid is light enough to trigger from a dash switch or the factory horn circuit via a relay.
- Plumbing. The kit’s 10 ft of 1/4” OD high-pressure hose connects tank to horn; the pressure switch automatically maintains 80–110 PSI. Use the manual drain periodically — a metal tank collects condensation.
- Mounting the horn. Use the included hardware on solid frame or crossmember structure. Our step-by-step install guide walks the whole job.
Any 12-volt vehicle with the space qualifies — pickups, SUVs, semis, and RVs. Budget a half day for a clean install: mounting the three components, running the hose, and wiring the relay circuit is straightforward work, but rushing the tank mounting or skipping the fuse is where most DIY problems start. Check your state’s rules before wiring it to the primary horn circuit; horn output at this level is regulated in many states, and our decibels guide explains what 152 dB actually means for hearing safety around the vehicle.
Sources
- Wolo — Model 850-858 Siberian Express Chrome PRO product page — all specifications (dB, PSI, Hz, materials, dimensions, solenoid, compressor, tank, hoses, weight), $389.99 list price, out-of-stock status, and the ABS-vs-metal copy discrepancy
- Wolo — Model 852-858 Siberian Express Chrome PRO product page — spec-table cross-check: the same all-metal construction line appears on the ABS-trumpet 852, and backs the 852 chrome variant mentioned in What it is
- YouTube — WOLO SIBERIAN EXPRESS CHROME TRAIN HORN SERIES (official Wolo channel) — manufacturer sound demo of the chrome Siberian Express series
- Summit Racing — WLO-850-858 listing — retail listing cross-check
- Amazon — Wolo 850-858 Siberian Express Chrome Pro listing — retail availability cross-check
- XDP — Wolo 850-858 Siberian Express Pro Chrome Train Horn Kit — retail availability cross-check
- Zoro — Wolo Train Horn, Air System, Siberian Express 850-858 (G8589528) — retail availability cross-check
Train Horn Hub aggregates publicly available data. We do not test products in-house. All trademarks belong to their respective owners.
A strong-value complete train horn package for pickup and semi owners who want a chrome showpiece with a real low-range chord and everything included — if you can catch it in stock, and you can live with an undisclosed dB test distance.
Frequently asked questions
Quick answers to the questions people ask most about this topic.
- How loud is the Wolo 850-858 Siberian Express Chrome PRO really?
- Wolo rates it at 152 dB when supplied with 90–110 PSI from the included air system. That is a manufacturer claim, and Wolo does not disclose the test distance, so treat it as a spec-sheet number rather than a field measurement.
- Are the trumpets metal or ABS plastic?
- Wolo's page is contradictory: the specification table lists all-metal horn construction with chrome-plated trumpets, while the description paragraph on the same page says the horn is engineered from reinforced ABS plastic. The same all-metal spec line appears on the ABS-trumpet 852's page, so treat the chrome finish as confirmed and the underlying material as unconfirmed.
- Does the 850-858 come with everything needed to install it?
- Yes — it is a complete kit: the triple-trumpet horn, a 12-volt compressor, a 2.5-gallon metal tank with pressure switch and gauge, a 12 V/250 mA solenoid, 10 ft of high-pressure hose, a 20 ft filler hose, brass fittings, and mounting hardware. You supply wiring, a relay, a fuse, and a switch.
- How much space does the kit need in a truck?
- Plan for the horn at 16.5 by 14.75 by 11 inches, the tank at 17.25 inches long, and the compressor at about 10.25 inches. Most owners mount the tank and compressor under the bed or along the frame rail of a full-size pickup, with the horn on the frame or behind the bumper.
- What does the Wolo 850-858 cost and where can I buy it?
- Wolo lists the kit at $389.99, though it was out of stock at Wolo direct at review time. It is also listed at Amazon, XDP, Zoro, and Summit Racing, so expect availability to vary by retailer.
