BRANDS
Prima Stainless Fittings
$9.95 - $32.95
Detail Division · Inspection Report
MTM PRIMA Stainless Quick-Connect Fittings
US-machined 303 stainless pressure washer fittings held to ±0.005" (127 µm), with EPDM seals. They make a tighter, more repeatable seal than standard import fittings, and you can feel the difference before they ever see water.
LINEAR±0.005"127 µm
ANGULAR±1°working surfaces
Part
PRIMA QC fitting
Mfr
Veloci Performance / MTM
Material
303 stainless steel
Steel origin
Pittsburgh, PA, USA
Process
100% machined
Seal
EPDM o-ring
Inspection
Digital comparator
Finish
Deburred · washed
01 · The problem
Fittings don't fail. Seals do.
Stainless fittings almost never wear out as metal. They leak because the plug doesn't land in the same place on the o-ring every time. A loose union lets the plug nose wander, water finds the gap, and the o-ring gets chewed up faster than it should.
Typical import fittings are made to looser tolerances and are often left with sharp, unfinished edges. They work, but they leave room for slop.
The PRIMA answer
Machine every surface tight enough that the union has nowhere to go. When a PRIMA plug engages a PRIMA coupler, the plug nose is driven into the same spot on the o-ring every time. There's no deflection and no bypass, just a proper seal.
02 · Specification
What makes PRIMA different
| Material | 303 stainless steel · Pittsburgh, PA303 is the free-machining stainless grade. It cuts cleanly enough to hold tight tolerances and leave a smooth finish, which is why it's the right choice for a precision fitting. Its corrosion resistance is excellent for water and detailing chemistry. The real gain over standard fittings is fit and finish, not rust-proofing. |
|---|---|
| Manufacturing | 100% machinedEvery surface is cut to spec. |
| Tolerance | ±0.005" (127 µm) · ±1° on working angular surfacesTighter tolerances mean less play between plug and coupler and a more consistent seal over the life of the fitting. |
| Quality control | Digital comparator inspectionProfiles are checked against spec optically, not just by eye. |
| Finish | Deburred · beveled · washedSharp edges are machined off. That's what gives the fittings their smooth feel and action. |
| Seal | EPDM o-ringHandles hot water, alkaline and acidic cleaners well. See the chemical note below. |
03 · Out of the pack
What you'll actually notice
| Standard fitting | PRIMA | |
|---|---|---|
| In hand | Sharp, angular, coarse edges | Beveled and smooth. It almost feels soft. |
| Engagement | Loose, with some wobble in the union | Firm and positive. It takes deliberate force to connect and release, with no slop once seated. |
| Seal | Plug position varies, and water can work around the o-ring | The plug nose lands in the same spot on the o-ring every time |
| Corrosion | Depends on alloy; often brass or unspecified stainless | 300-series stainless. Excellent in water and detailing chemistry. |
04 · Section A–A
Why the seal is repeatable
Schematic · not to scaleLocking mechanism omitted for clarity
Try this before installing: connect a PRIMA plug to a PRIMA coupler and watch the plug seat. The tolerances drive the nose into the exact spot it needs to sit on the o-ring, so there's no room for water to deflect around it. Every connection seals the same way.
05 · Process log
How every fitting is made
OP 10Source
303 stainless from Pittsburgh, PA
PASS
OP 20Machine
100% machined to ±0.005" / ±1°
PASS
OP 30Inspect
Profile verified on a digital comparator
PASS
OP 40Finish
Deburred, beveled, washed
PASSSeal compatibility: read before using solvents
EPDM handles hot water, alkaline degreasers, acidic wheel and mineral cleaners, and most detailing chemistry well. It does not tolerate petroleum-based products.
- Avoid running petroleum solvents, oils, or solvent-based tar removers through these fittings.
- Citrus (d-limonene) degreasers can swell EPDM over time. Rinse after use.
- A swollen or nicked o-ring will leak no matter how precise the fitting is. Replace the o-ring, not the fitting.
06 · Application
Who these are for
Who
Professional detailers, mobile operators, and enthusiasts who are done with leaky, gritty quick-connects
What
Stainless quick-connect couplers and plugs for pressure washer lines and accessories
When
New builds, or upgrading worn and leaking QC points on an existing setup
Where
Hose-to-gun, gun-to-lance, foam cannon, and any other QC union in your system
Why
A repeatable, leak-free seal and smooth action, connection after connection
Keep it clean
Tight tolerances don't like grit. Don't drag connections through dirt, and rinse them after each job.
Inspect seasonally
Check o-rings for flat spots, nicks, or swelling. A worn o-ring is the most common cause of leaks.
Replace the seal
The stainless will outlast your machine. Keep spare EPDM o-rings on hand.
07 · Is it worth it?
That's your call
Tighter tolerances mean a lower failure rate most of the time. There's a trade-off, though, and anyone who's run a tight-tolerance firearm knows it: precision parts are less forgiving of dirt. Keep these clean and out of the mud, and they're an upgrade you can feel, not just one you can see on the receipt.
There is no perfect system. Water carved the Grand Canyon, and given time it will go wherever it wants. With stainless, the failure point is almost never the metal. It's a degraded o-ring or a dirty connection. Keep them clean, inspect them seasonally, and these should be the last fittings you buy for that spot on your rig.
08 · FAQ
Common questions
Why are PRIMA fittings harder to connect than my old ones?
Because there's less clearance between plug and coupler. The firm engagement is the tolerance at work. It means the union has no room to wobble or let water bypass the o-ring.
Is 303 stainless more corrosion resistant than other stainless fittings?
Not meaningfully. 303 is chosen for machinability, which is what allows the tight tolerances and smooth finish. Its corrosion resistance is excellent in water and typical detailing chemistry, but the reason to buy PRIMA is fit and seal, not rust resistance.
Can I mix PRIMA fittings with standard plugs or couplers?
They'll connect to standard quick-connects of the same size, but you only get the full benefit, a seated plug nose and repeatable seal, when both halves of the union are PRIMA.
What chemicals should I keep away from the EPDM seals?
Petroleum solvents, oils, and solvent-based tar or adhesive removers. Citrus degreasers can also swell EPDM with repeated exposure. Water-based alkaline and acidic cleaners are fine.
Will I ever need to replace them?
The stainless body is very unlikely to wear out. Expect to replace o-rings periodically, and keep the fittings clean so grit doesn't damage the sealing surfaces.
Where are PRIMA fittings made?
Veloci Performance began machining the PRIMA line in the USA in 2023, using 303 stainless sourced from Pittsburgh, Pennsylvania. Detail Division ships them nationally and internationally.
Made in USASteel · Pittsburgh, PA
In 2023, Veloci Performance moved production of a select group of pressure washer fittings to the United States. Material and shipping costs were squeezing the global market, and they saw it as a chance to build something better instead of cheaper. PRIMA is the result: American steel, machined to a tolerance most fittings never see.
worth a look
