Round Ceiling Diffuser, Hon&Guan Soffit Vents 4 Inch Adjustable Ceiling Vent, Stainless Steel Vent Cover Wall Vent Exhaust Vent for HVAC System.

The product describes it as "push in" which refers to the installation, not the air inlet adjustment.There is an install sleeve that the unit pushes into and twists like a screw to tighten it in.In order to change the opening you have to unscrew it from its sleeve and turn the screw from the back. A better design would have been to put a horizontal line indentation in the front of it that you could turn it with a coin to rotate and thus adjust the amount of air passage without having to dismantle it.If you never want to adjust it then you just set it one and then let it done, but I want to adjust it open and closed every day.

These appear to be made almost entirely of aluminum, and seem sturdy enough for occasional adjustment, but the screw that lets the pieces close and open seems a little wobbly, and probably wouldn't take daily adjustment for more than a month or so. I intend to set it and forget it, so I feel like it's a good value for the money.

Look is nice however during shipping the center adjustment is bent. Cheap.

The vent cover arrived quickly, and is made of nicely bushed steel, but it just doesn't stay in the ceiling. When the collar is in hand, the vent cover snaps into it fine, but when the collar is mounted in the ceiling, the cover just will not fit into the collar deep enough to hold. It just keeps calling out under its own weight. Poor design is the issue. I am currently looking of ideas to make what I have work, probably might use self tapping sheet metal screws and a duct extender. If it works, I'll update this review. For now, I cannot use this overpriced trash. The plastic one this replaces goes deeper and it holds in place, why can't this thing be made like the plastic one? It just needs an extra couple inches in the collar depth to make it work. So for now, it gets 3 stars. If I can get I to work, I'll give it 4, of not, it'll get a 2.

The description of the product is misleading...it states on Amazon, "you can press panel to adjust the air volume". This is not actually true, you need to spin the centre section of the vent to open and close and if you want to maintain a position you need to go on the other side of the vent an tighten a nut other wise the centre section flops around.It might not be such a big deal if you have access to the back of the vent, however in my case we are using it outside in a small shed and I can't image how easy the centre section will be to move once we get snow and ice on it. You might want to mention its for internal use only, and change the operating statement. For me this will was a bad purchase heading to the garbage.