Deflecto 4” Duct Connector, Aluminum with Bead and Crimp, Silver, 3” long

A compact fix for a common ducting headache

Sometimes the simplest hardware makes the biggest difference. I picked up this 4-inch aluminum duct connector to rejoin a dryer run after a laundry room refresh and ended up using it again on a bath fan replacement. It’s a straightforward piece—3 inches long, crimped on both ends to join two female duct ends—with a center bead that acts as a stop and stiffener. Nothing flashy here, just a small connector that either earns trust or causes headaches depending on the build and fit. After installing it in a couple of scenarios, I have a clear sense of where it excels and where it asks for some care.

Design and build

• Format: 4-inch diameter, 3-inch overall length
• Material: Fire-resistant aluminum
• Ends: Crimped on both sides (male-to-male coupler)
• Feature: Center bead for strength and clamp indexing
• Ratings: Up to 80 psi, 5,000 FPM, -100 to 430°F

The center bead is the quiet star here. It stiffens what is otherwise a light-gauge aluminum tube and gives you a positive stop so each duct slides on to the same depth. It also helps clamps sit squarely. The aluminum is corrosion-resistant and sufficient for residential ventilation temps; a 430°F operating ceiling is well above anything a dryer or bath fan will produce.

That said, the gauge is light. This keeps it easy to shape by hand and reduces the chance of galvanic mess if it gets damp, but it also means it can deform if you muscle it or over-torque a clamp. Edges from the crimps are reasonably clean on the sample I used, but I still glove up—sheet-metal edges are sheet-metal edges.

Installation experience

My first use was reconnecting a semi-rigid aluminum dryer transition duct to an existing 4-inch rigid line. Both sides were female, so a double-crimp male coupler like this is the right part. The install sequence was simple:

1) Dry-fit both ends to check roundness and insertion depth to the bead.
2) Lightly massage any out-of-round duct with fingers and a slip-roller motion on the connector itself.
3) Slide the ducts on until they meet the bead.
4) Seat worm-gear clamps over the plain (un-crimped) duct and tighten evenly.
5) Seal the joint with UL 181 foil tape.

The slip fit was clean on the semi-rigid side and snug on the older rigid run. I needed a tiny tweak with HVAC pliers to round the rigid duct’s mouth; that’s normal on older metal. The bead made it much easier to set both sides evenly and kept the clamps from walking while I tightened them.

A note on fasteners: on venting that carries lint (like a dryer), I avoid sheet-metal screws protruding into the airstream. They become lint catchers. Properly seated clamps and foil tape are enough here.

On the bath fan, the connector again did its job, though the shorter 3-inch body gives you about an inch of insertion depth per side once you account for the bead. That’s fine in most cases but doesn’t leave a lot of margin if a duct end is rough or out of round. If you know your joint will be under tension, a longer coupler may make sense.

Fit and sealing

Out of the box, the crimps were consistent and round. Because the metal is light, it’s forgiving: if your duct is slightly oval from storage or handling, you can coax it back to round without tools. The flip side is that it also yields if you crank a clamp too hard. Tighten until snug and then a quarter turn—no more. With clamps set and foil tape applied, I got no perceptible leakage in a simple tissue test while the fan was running. On the dryer, airflow felt as strong as the previous rigid-to-rigid connection.

The bead helps prevent “creep” over time. It’s a mechanical indexing point that keeps both sides seated where you left them. That matters if you occasionally pull the dryer forward for cleaning; joints that walk can eventually pop.

Durability and handling

Aluminum has obvious corrosion resistance advantages over uncoated steel in damp spaces, and the temperature rating here is more than adequate for residential venting. But let’s be candid: this is a light-gauge part. It will hold a clamp and tape just fine; it will also kink if it’s crushed behind an appliance or tossed loose in a tool bag. Treat it like the thin sheet-metal component it is. If you anticipate repeated disconnections (for quarterly duct cleaning, for example), the crimps will loosen their crisp shape over time with rough handling. That’s not a failure so much as a trade-off with a lightweight coupler.

If you want something that shrugs off abuse, a heavier-gauge galvanized steel coupler is tougher and less prone to deformation. The downside to heavier steel is weight, a bit more effort to shape on old ducts, and the same need to seal the joint.

What it’s good for

• Dryer vent repairs or extensions with two female ends
• Bath fan and range hood vent runs with 4-inch duct
• Short, tight spaces where a compact coupler is an advantage
• Situations where corrosion resistance and a clean slip fit matter

The 5,000 FPM velocity spec and the temperature range are standard and more than adequate for these use cases. In my installs, the connector stayed cool to the touch and quiet—no buzzing or rattling under normal fan vibration.

What it’s not for

• Combustion venting (furnaces, water heaters): use the code-approved vent type (e.g., B-vent), not an aluminum coupler.
• High-pressure ducting: the psi rating here is a curiosity more than a practical spec; typical HVAC static pressures are a tiny fraction of a psi, but this isn’t a pressure-rated pipe fitting.
• Frequent service joints that get opened and closed often: go heavier-gauge or consider a banded “no-screw” connector with an integrated clamp.

Tips for best results

• Pre-round your duct ends; even a small oval makes a big difference with a short coupler.
• Use UL 181 foil tape over clamps for a leak-tight, code-friendly seal. Skip cloth “duct tape.”
• Don’t over-tighten clamps; you’ll collapse the aluminum crimp and create leaks.
• Position clamps just shy of the bead so they seat against it without riding onto the crimp.
• Plan your joint so the coupler isn’t supporting weight or tension; ducts should align naturally.

Value and alternatives

This connector sits in the “no-brainer” category for quick fixes: inexpensive, commonly stocked, and easy to install. If you know you’ll be rough on the joint or need extra insertion length, a heavier-gauge steel coupler or a longer 4–6-inch connector is worth the modest upcharge. For transitions at the back of a dryer, I also like semi-rigid kits with integrated draw-bands, which simplify installation in very tight clearances.

Final thoughts

The 4-inch aluminum connector did exactly what I needed it to do—join two female duct ends quickly and securely—without introducing noise, leaks, or added restriction. The center bead is a smart detail that improves clamping and alignment, and the compact length is genuinely helpful behind appliances and inside soffits. Its limitations are just as clear: the light gauge demands a gentle hand, and it’s not the right choice for joints that will be disturbed frequently or subjected to mechanical stress.

Recommendation: I recommend this connector for typical residential ventilation tasks—dryer vents, bath fans, and range hood runs—where you need a simple male-to-male coupler in a tight spot and you’re willing to seal it properly. If you prefer a component that feels more substantial or expect to service the joint often, step up to a heavier-gauge steel version or a longer coupler. For most everyday fixes, this aluminum piece is a practical, tidy solution.