I bought this adapter to reduce the 4 inch opening on my delta planner but it is the exact size as the opening on the planner. I though the purpose of a reducer was to fit 4 inch openings without another adapter. I had to buy a 4 inch to 4 inch coupling to make this work.

you would think this fitting is all you need to be able to use a shop vac,
it wont work; unless you also buy a 4" hose and other fittings?
dont waist your money, (there are other fitting out there)

This item works as advertised. I bought this when I was setting up my dust collection system and wanted to connect it to my spindle sander (which takes a shop-vac type of connector). I was not careful when I read the dimensions of this reducer. This will not work for such purpose. It will work if you want to connect your shop-vac to it and then connect the other end to the 4" connector of a machine. The problem is that a shop-vac is 2 1/4" and not 2 1/2. There is a different adaptor you could use for that.

I purchased this with a dust collection hood for my planer. The hood has a 4" port. I thought that I could plug my shop vac hose into this adapter and then plug the adapter into the hood. My mistake! This will allow you to adapt a 4" hose to a 2.5" hose, but I had to tape the adapter to the hood as both ends of the adapter are female.

The picture seems to show an adapter with a tapered transition from the large to the small dimension. In fact they have a 90 degree step making them not suitable if you are using a shop vac on the small end to exhaust a tool with a large diameter output. If you want to connect a smaller vac hose to a large dimension shop system they would be OK. I just threw them away.

the 4 inch to 2-1/2 in reducer is useless with the Jet saw I ordered. The 4 inch end is exactly the size of the opening of the dust collector in the saw, so it neither goes into nor around the opening. The 2-1/2 inch end fits into the dust collector hose perfectly. I rated this one star because 0 was not available

This reducer did fit my Jet band saw because it has a 4 inch cast iron port. I also ordered the 4 inch quick disconnect so I used a pc of 4 inch pvc to connect the 2 items and they work fine.

So we used this reducer to fit a hose through the 2-1/2 inch part to release the hot air made from the air-condtioner even though we had to use a lot of duct tape. It works but I guess that the hose was too long and it blew a fuse. Overall this item was shipped as described!

A basic plastic 4" to 2.5" dust collection system reducer. Quality but nothing magic.

When buying a Grizzly 14`` bandsaw, a riser kit, a mobile platform, extra blades, and some abrasives, all shipping from different places, this simple .89 cent reducer cost over $10.00 to ship. Surely this was a mistake that will be corrected, if not , Amazon will get no more of my business and I will spread the word to the best of my ability.

I used this adapter to go from my tablesaw to shopvac which is...suprise,suprise... 4" to 2.5"! Only problem was the 4" side would not fit into the outlet of the saw. This is because both are tapered to accept a hose. So...I cut of piece of 4" dryer hose about 3" long, and strapped them up with the metal bands. Works for me with nominal dust.

WATCH OUT!
My Jet JW1044 4" to 2 1/2" adapter arrived today. Because I needed one badly I paid $6.81 for the part and $9.99 for shipping BUT I needed an adapter that was 4" INSIDE diameter on the large end and 2 1/2" inside diameter (nominal) on the small end.
The item I received, marked "JW1044", is 4" OUTSIDE diameter on the large end.
THERE IS NO INDICATION OF THE TRUE, USEFUL, SIZES OF THE ENDS OF THIS ADAPTER IN THE AMAZON LISTING!
WATCH OUT!

I used a few of these in my war against workshop dust: on the router table, on my DeWalt 746 tablesaw, on the miter saw, and on my Grizzly benchtop belt/disc sander. I have to say that if you want to reduce 4" flex hose or ducting to a 2 1/2" port, this is the absolute BEST way to go. The plastic is quite strong and always a consistent 4".

Highly Recommended!!!

This connector is female on both ends. I didn't pay close enough attention to the description while shopping and ordered it expecting to be able to connect my 2 1/2" shop-vac hose to the 4" dust collection port on my table saw. Needless to say, I was dismayed to discover the diameter of this adapter and the port on my table saw were the exact same OD - meaning it doesn't fit without a 4" hose between the two.

If you do end up in the same situation as me - don't give up hope. I aligned the adapter and DC collection and wrapped a length of duct tape around both. A solid connection that converts my tablesaw from 4" to 2 1/2" and works great! Hope that helps those who were in the same situation as I. For those who have yet to purchase, just make sure this is really the product you are looking for.

In case anyone is really concerned, the actual construction of this adapter is solid and accurate.

The 4" side fits my 4" quick release well enough. The 2 1/2" side fits the END of a 2 1/2" hose. This does not work well if you intend to go directly from your 2 1/2" port on your machine to your 4" dust collection hose. The adapter and the port will more than likely be the exact same size (two female sides).
The adapter is also not shaped the same as in the picture. It is not funnel shaped but a 2 1/2" tube and a 4" tube connected by a flat piece.

Inially I was upset with this, it didn't fit. Well, my mistake, I didn't see the OD part. Anyway, I found the perfect spot. It fits the 2 1/2 inch port for the Dewalt table saw perfectly. I have now replaced the elbow fitting that came with the saw that for some reason is set to point at the saw leg, making it useless. Now my saw is easy to connect to my 4 inch collection system.

The description by Robert Feeser (one of the top 500 reviewers in Amazon) explains 'This adapter is great for mating the popular 2 1/2" vacuum hose size to your 4" hoses. This 4" is a male end that will fit well into your 4" hose acting as a female, and the 2 1/2" end is a female that will receive your 2 1/2" hose as a male. :-) I don't know why that is so funny, but it strikes me that way. That is the best description I can give it. These Jet adapters fit perfectly'.

The adapter I received has a flat interface, not the funnel style shown. That makes a difference if using the piece with the airflow going from 4" to 2 1/2" due to increased turbulence.

If you're planning to use this downstream from large to small diameter then I suggest you find one that is indeed funnel-shaped.

I bought this to connect my 4" Jet hose to the 2 1/2 port on my bandsaw and table saw. All the current research is to keep the dust collector draw (I have the Jet 1100) at 4" (6" on a planer) until right before the machine (actually to rebuild any machine to accept a 4"). The ad does say it's 2 1/2 OD and silly me, I didn't bother measuring the 2 1/2 at the tool end. Guess what? They're both 2 1/2 OD so they do NOT fit together. In my opinion, this is a worthless adapter - as it doesn't advertise as a hose to hose connector, and hooking a 2 1/2 shop vac to a 4" opening at the tool is like trying to suck dust out of a garbage can with a straw - the physics are wrong - this should be only used for reducing a 4" hose to 2 1/2" at the tool, but again it's the wrong diameter. A proper adapter should be either 2 1/4 OD or 2 1/2 ID to fit over the tool's port. Does anyone know where to find such an animal? I finally found a rubber plumbing connector (at Home Depot) that joined the two 2 1/2 OD fittings together. This works but we should've have to do this for a peice of plastic they charge over $5 for. Please do not hook a shop vac to a jointer and expect to remove the 1 to 5 micron diameter dust particles that can cause COPD (lung disease), you'll only get the chips, sort of.

I ordered this because it was recommended by Amazon as an adaptor to smaller hose size, but in fact it does not fit. The diameter of the Woodstock Dust Collector is 4"; the adaptor is 3-7/8" actual, so it won't slide into or over the housing. Now I have to find yet another tube to connect the two parts. Dumb solution!!

There's nothing wrong with this part if it's what you need, but I rated it one star just to point out the following: As other reviewers mention, this JW1044 is hose-to-hose only. You get better dust collection if you don't have to run through another 10' of hose just to hook things together, and Jet does make a 4" to 2 1/4" reducer part # JW1000. How can we get Amazon to stock it???

This adapter had the proper O.D. on the 2.5" side so that the end of my shop vac. hose fit in properly. But the dust chute on the 6" JET Jointer I bought from Amazon.com has the same O.D. as the nominally 4" side of this adapter (so they don't fit together well). No big deal for me: what I did was take a thin-blade hack saw, slice four cuts at 90 degree separation in the walls of the ~4" end, slip it over the dust chut on the jointer, wrap duct tape around the outside of the adapter's large end (while attached to the jointer), and now I've got a removable adapter that actually works. If you can't find the right part (I could not, looking high and low), this is a reasonable solution for those who can handle the minor frustration of the imperfect solution.

This adapter is great for mating the popular 2 1/2" vacuum hose size to your 4" hoses. This 4" is a male end that will fit well into your 4" hose acting as a female, and the 2 1/2" end is a female that will receive your 2 1/2" hose as a male. :-) I don't know why that is so funny, but it strkes me that way. That is the best description I can give it. These Jet adapters fit perfectly.
To securely connect this adapter, I suggest that you buy the Jet wire connectors, instead of the standard band clamps. Since most dust collection hoses have a wire running through them, band clamps can not compress them. The Jet wire clamp goes around the wire in the hose, and it grips the material directly to the fitting. I tried using the band clamps, and after having to reattach them on a regular basis, I went to the Jet 4" wire clamps, that is why I am making such a big deal out of it. I have never had to retighten, or reinstall the hose on the adapter since. The wire clamps work perfectly. Highly recommended.

I bought the adapter because I want to use my shop vac with my new Delta table saw which has a 4" dust collection port. It won't do that--it is the same diameter on the big end as the dust port on my Delta (or any other piece of equipment). I had expected that it would fit INTO the dust collection port and then I could hook up my shop vac. It won't do that, so I am still looking for one that will. If you are connecting hose to hose it should be fine, but I gave it the 1 star so you would notice the issue I raised.

I bought this thinking that I could put my vaccum accessories on my dust collector - They do not fit. This is a hose to hose only fitting. It is built well for a hose to hose connector, so I give it 5 for that purpose only.

It was what I expected. I wish the transition was shaped like a funnel instead of a flat wall. But it works.

Just be advised, this is not a standard 4-2.5 reducer, this thing will only work with a jet machine 4" coupling.

You need a a piece of hose between the adapter and jointer since they both have the same OD. It is kind of anoying. It should have come with a piece of hose as well.

After purchasing the adapter, I found that it does not fit on the dust shield of my Jet Table Saw without a piece of 4" hose between the adapter and shield. After installing the hose, the adapter works fine.

Great for using with a Sears or equvilant shop vac size hose at 2-1/2". Don't forget to get a piece of 4" hose to go with it since it does not directly hook up to dust collector on saw.

Great for using with a Sears or equvilant shop vac size hose at 2-1/2". Don't forget to get a piece of 4" hose to go with it since it does not directly hook up to dust collector on saw.

If you need to step down in the DC system, which is recommended, this works great. The ends are to size stated, the hose fit easily and the wire clamps put it all together snuggly. The fitting allows you to step down from a larger main line to smaller branch lines near the machine, thus increasing the air suction, where it's needed most, by the machine.

If you need to go from 4" to 2 1/2" it does the job!