Upon opening the two diffusers I purchased I discovered what I could only think must be white mold inside the folded segments of one. Otherwise I might have said this was a good product.

I had purchased a Fotodiox rectangular softbox, and while I'm a Fotodiox fan, their 9" box flopped over and blocked a lot of my light. When I saw this product, which looks like a smaller version of my 24"X24" softboxes I knew I had the answer. Now that it has arrived, I'm not disappointed. I use the softbox attached to my speedlight on a flash bracket which places the entire assembly high above my camera. When shooting up close (2-4 ft.) the softbox creates soft, smooth shadow transitions. It isn't a large softbox of course, so when you back up a bit, reducing the effective size of the light, the shadows become more defined quickly. Usually, I use this along with a 24"X24" softbox or a 43" umbrella on a pole and held by a VAL as a main light and my small 9" softbox on my flash bracket as fill. This is a great two light event setup and gives me a ton of options and flexibility.
The opening in the 9" softbox fits snuggly on my YN 565 EX flash (virtually the same size as a Canon 580 EX) and the two sets of wide velcro straps won't let go anytime soon. One thing I discovered right away in regards to mounting my flash inside the unit is to not strap the flash into the softbox firmly. Doing so causes the flash to point to the bottom of the softbox. Letting the straps have a little play will keep the flash head pointed forward and still keep the softbox from falling off.
Four stars? This thing isn't going to fall apart on me...especially since I'll never fold it back up and put it back into it's case. But the stitching could be a little better. Still...for $15? It's a very useful modifier.

I purchased this specifically for off-camera flash in macro shooting scenarios, and it is perfect for that. Seems solidly made, and the double diffusion evens out the flash very well (at the cost of some output power). At the close distances I use this for macro, it doesn't matter about the output loss. I'm also interested in using this on a flash bracket for events. Seems like it might work well for medium distance (6-8') shots. Anything further will probably not benefit much from the small diffuser -- but we'll see!

I regularly use small, inexpensive soft boxes on speedlites when traveling, usually for off camera flash, as I find they noticeably improve the resulting picture when shooting portraits from up close.
For years I have used very simple ones that tend to not hold well together and break easily but are otherwise downright cheap to buy ($10 or less), very light and can fit in any pocket of any bag.
Except for travel portrait I also use them for macro photography where stacked-up macro rings eat so much light that you can't really consider going without some additional lighting.
The problem with them in addition to their flimsiness is the lack of double buffering resulting in a somewhat uneven lighting pattern, especially visible when shooting macro, and their size really too small for portrait.

This 9-inch softbox solves these two problems: double buffering produces a very even light field and 9 inches is bigger yet still a manageable size when doing macro or for travel.

The quality of the fabric seems right; the interior is very reflective and the results match my expectations for the price and design.
The lips on the side do a decent job at controlling light spillage and restricting illumination to where you want it.

Now it is not perfect.
It folds to a manageable flat form that can be stored away in a pouch, but the folding is pretty stressful on the frame which is made of a springy wire of a gauge more suitable for soft boxes twice or thrice the size, resulting in a required folding effort too high for the size of the softbox. This results in deformations of the size of the frame on the inner fold once folded, and my questioning of how many folding/unfolding it will withstand.
So far maybe 20 and it works just fine.

Another sticking point is the way the speedlite is attached to it. Its head is to be stuck in the hole at the back of the soft-box, which features an elastic ring of fabric for light tightness (works very reasonably) and two pairs of velcro straps to attach at the back of the head. This means that your speedlite must be folded in the classic "cobra" position, or the straps would slip; and it also means that the actual angle of the soft box on the flash is somewhat haphazard.
This is not necessarily a drama considering you have double-buffering to avoid hot spots on the front buffer, but if you add to that the impetus to rotate the head 90 degrees to a side to expose the sensor used for remote triggering the speedlite (canonistas will know what I mean) it can become somewhat flimsy.
Then of course it remains a small soft box - this is fine for travel portrait or macro but it remains utterly inadequate for your usual fashion shoot.

All in all for the price a good acquisition. It will not take good pictures for you but if you know what you are doing it should help you a lot.

I was looking for something to diffuse the light when I don't have a good place to bounce light from and this fits the bill. Easily mounts to my Metz 44 AF-1 flash. Not extremely heavy duty, but will work will for the few times I need to use it. One down side is that it if my flash is mounted on-camera it will block my AF assist lamp, so I need to use it for fill light only or use it off camera.