The AC Infinity Duct Reducer, 150 mm to 100 mm is a galvanised steel adapter cone that joins two different duct sizes. Crimped, ridged rims with a raised lip at both ends grip flexible or rigid ducting, and the zinc coating keeps it from corroding in a damp subfloor or a humid grow room.
It exists for the moment the kit you have and the opening you have do not match — a bigger fan meeting a smaller wall penetration, an existing vent you would rather not enlarge, or a filter one size down from the fan driving it.
What people use it for
Home ventilation
- Meeting an existing 100 mm wall vent with a 150 mm fan
- Adapting a duct run to an appliance outlet of a different size
- Stepping down at a grille or termination without cutting a bigger hole
- Joining mismatched ducting on a retrofit
Hydroponic ventilation
- Running a 150 mm fan onto a 100 mm carbon filter you already own
- Adapting between a tent port and a different-sized duct run
- Stepping down into a smaller silencer or filter box
- Connecting mixed-size kit across two tents on one run
Full specifications
| Manufacturer | AC Infinity Inc. |
| Product / model | Duct Reducer 6″ to 4″ / AC-SDR64 |
| UPC | 819137021334 |
| Duct opening sizes | 150 mm (6″) to 100 mm (4″) |
| Cone length | 130 mm |
| Material | Galvanised steel |
| Finish | Zinc coating, corrosion resistant |
| Rims | Crimped and ridged with a raised lip, both ends |
FAQ
Can I use it the other way round, to step up?
Physically yes — it is a cone with two ends and no direction. Expanding a smaller fan into bigger ducting gains you no airflow, because the fan is still the limit, but it is occasionally the only way to meet an existing large opening.
How much airflow will I lose?
It depends entirely on how much of the run is reduced and how many bends sit in it, so any single figure would be invented. The rule that holds: keep the reduced section short and the loss is minor; run the whole thing narrow and expect a real drop.
Will it make my fan louder?
Usually a little, yes. The same volume of air through a smaller opening moves faster, and faster air is noisier. If noise matters — a fan under a bedroom floor, or a tent in a living space — keep the reduced section short and consider acoustic ducting or a silencer on the run.
How do I seal the joints?
Slide the duct over the ridged ends, then finish with a stainless duct clamp or foil tape. Both ends need it. A reducer packs two joints into a short space, which makes it a natural leak point if you rush it.
What combinations do you stock?
150→100 mm and 200→150 mm. Stacking two reducers to step further works but adds joints and resistance — ask us before you order if that is what you are planning.
Is this genuine AC Infinity stock with an Australian warranty?
Yes. Quick Bloom Lights is the official Australian importer and distributor for AC Infinity. Stock is held in Sydney, orders ship domestically, and the two-year warranty is handled here rather than through an overseas seller.