- +Dual chrome-plated stainless ProBlaster trumpets with a genuine, throaty tone
- +Complete bolt-up kit — horns, waterproof 6270RC compressor, 0.5-gal tank, and fittings in one box
- +Compact footprint fits trucks and SUVs where larger triple/quad kits won't
- +Sound rating is published with its PSI (149.1 dB at 150 PSI), more honest than dB-only specs
- +Backed by Kleinn's nationwide dealer network and vehicle-specific add-on hardware
- −0.5-gallon tank gives only short bursts before the compressor has to catch up
- −dB rating omits the test distance, so cross-shopping against rivals is imprecise
- −Only a 1-year limited warranty — short next to some competitors
- −Chrome HK2 lists near $360, pricier than several louder triple kits
- −No published chord frequencies for buyers who care about exact tone
Methodology
This review aggregates publicly available information from manufacturer specifications, retailer listings, and verified user reviews. We do not perform hands-on testing. The figures below come primarily from Kleinn’s official Model HK2 product page, cross-checked against Summit Racing’s listing and Kleinn’s broader catalog. Last reviewed: June 8, 2026. Where sources disagree on a number — and on the HK2’s decibel rating, they do — we say so rather than pick the loudest figure.
Quick verdict
The Kleinn HK2 earns a 4.0/5 from us. It is a complete, name-brand dual train horn kit that delivers a convincing locomotive tone in a footprint compact enough for a daily-driven truck or SUV. You get chrome-plated stainless trumpets, a waterproof compressor, a small steel tank, and the fittings needed to wire it up — all in one box. The two things holding it back from a higher score are the modest 0.5-gallon tank, which limits how long you can lean on the horn, and a one-year warranty that trails what some rivals offer. If you value brand support and a clean install over raw tank reserve, it’s an easy recommendation.
What it is
The Model HK2 is Kleinn’s compact dual-trumpet “ProBlaster” train horn kit, aimed at pickup and SUV owners who want serious volume without the bulk of a triple- or quad-trumpet system. “Dual” means two trumpets sounding together, which produces a fuller two-note chord than a single horn while staying small enough to tuck under a bed rail or behind a bumper.
Unlike a horns-only product, the HK2 is a full onboard-air package: the trumpets, an air compressor, a half-gallon reservoir tank, and a fitting pack all ship together. That makes it a true bolt-up solution for someone starting from scratch rather than a part you bolt onto an air system you already own. It’s offered in polished chrome (HK2) and a blacked-out XCR2.0 Stealth finish (sold as the HK2-1).
Specifications
| Spec | Value |
|---|---|
| Sound output | 149.1 dB at 150 PSI (test distance not disclosed) |
| Operating pressure | 120–150 PSI |
| Trumpets | 2 (dual ProBlaster) |
| Trumpet dimensions | 16.5” L × 7.25” W × 3.75” H |
| Trumpet material | Chrome-plated stainless steel |
| Air tank | 0.5-gallon all-steel, gloss-black epoxy finish |
| Tank ports | Five 1/4”-NPT ports |
| Compressor | Model 6270RC, waterproof; 25% duty cycle at 100 PSI (72°F); ~1.15 CFM at 0 PSI |
| Power | 12V onboard air system |
| Finish options | Chrome (HK2) / Black XCR2.0 Stealth (HK2-1) |
| Warranty | 1-year limited (defects in materials & workmanship) |
| Price | ~$359.95 chrome; ~$339.95 black |
| Chord frequencies | Not disclosed |
A note on the loudness number: Kleinn’s own product page rates the HK2 at 149.1 dB at 150 PSI, and that is the figure we use. Some retailer listings quote higher numbers (for example 146 dB at 100 PSI and 153.5 dB at 150 PSI). Because none of these specify the measurement distance, treat them as ballpark marketing figures, not lab results. We dig into why distance matters in our guide to how far away you can hear a train horn.
What’s in the box
- Model 102 dual chrome air horns (the trumpet assembly)
- 6270RC waterproof air compressor
- Snorkel intake kit for the compressor
- 6260RT 0.5-gallon air tank with five 1/4”-NPT ports
- FIT12 fitting pack — pressure switch, safety valve, and drain valve
- Installation kit — wiring, airline, and mounting hardware
Because the kit is self-contained, the only major thing you supply is a 12V power feed, a ground, and a mounting location. That’s a meaningful convenience versus buying horns and an air source separately and hoping they’re matched.
Pros
- Genuine train-horn tone. Two chrome-plated stainless trumpets produce a deeper, fuller chord than the single-trumpet “air horns” in this price band.
- Truly complete kit. Horns, compressor, tank, switch, valves, and airline arrive together and are engineered to work as a system.
- Compact fit. The dual layout slots into tighter spaces than triple or quad kits, which matters on a daily driver. Our guide on where to mount a train horn covers the best spots.
- Honest-ish spec. Publishing the dB figure alongside its PSI (149.1 dB at 150 PSI) is better practice than the dB-only claims many budget brands rely on.
- Brand support. Kleinn sells vehicle-specific add-on brackets and replacement parts through a wide dealer network, so service down the road is realistic.
Cons
- Small reservoir. The 0.5-gallon tank stores only a brief blast of air; lean on the horn and you’ll hear it sag while the compressor refills.
- Distance not stated. Without a measurement distance on the dB rating, apples-to-apples comparison with rivals is guesswork.
- Short warranty. One year is on the lean side for a $300-plus air system.
- Chrome price. Near $360, the chrome HK2 costs more than several louder triple kits — you’re paying for brand and finish, not maximum decibels.
- No chord data. Kleinn doesn’t publish the trumpet frequencies, so tone-focused buyers are buying on faith.
Alternatives
- Kleinn HK6 — Step up to Kleinn’s triple-trumpet ProBlaster kit if you want a fuller three-note chord and don’t mind the extra mounting space. Our rating: 4.2/5.
- Kleinn 230 — The horns-only triple for buyers who already run onboard air and just need the trumpets, not another compressor and tank.
- HornBlasters Admiral 228H — A competing complete kit built around a larger 2-gallon tank, which holds far more reserve air for sustained blasts.
If you’re cross-shopping purely on price, our roundup of the best train horns under $200 covers cheaper options and the compromises they bring.
Install / compatibility notes
The HK2 is designed as a universal kit, so it fits most trucks and SUVs with a flat or boxed frame rail and a spare 12V circuit. You’ll need to find room for three things — the trumpets, the half-gallon tank, and the compressor — which is easier than placing a 2-gallon tank but still calls for a little planning. The included snorkel intake lets you route the compressor’s air pickup to a clean, dry spot, which is the single most important step for compressor longevity.
Wiring is straightforward: the kit’s pressure switch cycles the compressor to keep the tank between roughly 120 and 150 PSI, and the horn solenoid fires when you hit your chosen button or wire into the factory horn. We recommend a dedicated relay and an inline fuse on the compressor feed. The drain valve in the FIT12 pack should be opened periodically to purge condensation — skipping that is the leading cause of rust and frozen lines in cold climates, as covered in our winter prep guide. For a full walkthrough, see how to install a train horn, and if you’re unsure about pressure targets, our PSI explainer breaks it down.
One realistic expectation to set: with only a half gallon of stored air, the HK2 is built for attention-getting blasts, not minutes of continuous sound. The 25% duty cycle on the 6270RC compressor (at 100 PSI, 72°F) means it’s meant to run in short cycles with rest in between, not run flat-out.
FAQ
How loud is the Kleinn HK2 really?
Kleinn rates it at 149.1 dB at 150 PSI. Because the measurement distance isn’t published, treat that as a marketing-grade figure. In practical terms it’s loud enough to be startling at close range and clearly audible over traffic — but the small tank means sustained volume drops off faster than on a big-tank kit.
Is the HK2 a complete kit or just the horns?
It’s a complete kit. The box includes the dual trumpets, the 6270RC compressor, a 0.5-gallon tank, a fitting pack (pressure switch, safety valve, drain valve), and an install kit with wiring and airline. You supply power, a ground, and a mounting spot.
What’s the difference between the HK2 and HK2-1?
They’re the same kit in different finishes. The HK2 is polished chrome; the HK2-1 is the blacked-out XCR2.0 Stealth version. The black kit typically sells for a little less, around $340 versus roughly $360 for chrome.
Will the small 0.5-gallon tank be a problem?
It depends on how you use it. For quick blasts the tank is fine. If you want long, sustained sound or rapid repeated honks, a larger 1- or 2-gallon system — like the HornBlasters Admiral 228H — holds more reserve air and recovers between presses with less audible sag.
Is a train horn this loud street legal?
It varies by state, and many states regulate vehicle horn loudness or prohibit non-standard horns on public roads. Check your local rules before installing. We track this in our state-by-state legality pages — confirm your state before you wire it up.
Sources
- Kleinn — Model HK2 Dual Truck Horn Kit product page — primary specs (149.1 dB at 150 PSI, 120–150 PSI, dual chrome ProBlaster trumpets and dimensions, 0.5-gallon coated steel tank, 6270RC waterproof compressor and 25% duty cycle, included items, $359.95 price, 1-year warranty)
- Kleinn — Model HK2-1 Black Dual Truck Horn Kit — black XCR2.0 finish variant and ~$339.95 pricing
- Summit Racing — Kleinn HK2 ProBlaster Compact Dual Air Horn Kit — cross-check on tank ports, ~1.15 CFM compressor output, and alternate dB figures (146 dB at 100 PSI / 153.5 dB at 150 PSI)
- Kleinn — Model HK6 Triple Train Horn Kit product page — triple-trumpet alternative referenced in comparisons
The Kleinn HK2 is the right pick for truck and SUV owners who want a name-brand dual train horn with a real onboard air system in a tight package, as long as you accept the small 0.5-gallon tank and short warranty in exchange for the compact fit and build quality.
Frequently asked questions
Quick answers to the questions people ask most about this topic.
- How loud is the Kleinn HK2 really?
- Kleinn rates it at 149.1 dB at 150 PSI, but because the measurement distance is not published it should be treated as a marketing-grade figure. In practical terms it is loud enough to startle at close range and clearly audible over traffic, though the small tank means sustained volume drops off faster than on a big-tank kit.
- Is the HK2 a complete kit or just the horns?
- It is a complete kit. The box includes the dual chrome ProBlaster trumpets, the 6270RC waterproof compressor, a 0.5-gallon tank, a fitting pack with pressure switch, safety valve and drain valve, and an install kit with wiring and airline. You supply power, a ground and a mounting spot.
- What's the difference between the HK2 and HK2-1?
- They are the same kit in different finishes. The HK2 is polished chrome at roughly $360, while the HK2-1 is the blacked-out XCR2.0 Stealth version that typically sells for a little less, around $340.
- Will the small 0.5-gallon tank be a problem?
- It depends on how you use it. For quick attention-getting blasts the half-gallon tank is fine, but for long sustained sound or rapid repeated honks you will hear the volume sag while the compressor refills, and a larger 1- or 2-gallon system holds more reserve air.
- What warranty does the Kleinn HK2 come with?
- Kleinn covers the HK2 with a 1-year limited warranty against defects in materials and workmanship, which is on the short side next to some competitors.
