Product review (4 stars): It's fine, but it's not actually 24" from the outside ...
It's fine, but it's not actually 24" from the outside (that's the inside dimension).  It's more like 24.5 to 25" including the lip on the outside. It almost didn't fit into my alcove, and I ended up having to install it from behind to kind of force it to fit. But it's not really flexible, so if I had had about 1/2" less space it wouldn't have fit at all. You can't tell from the picture, but there are only three walls to the reservoir so the water will spill out onto the floor to warn you about a leak, so getting it under the washer is a bit of a challenge. Overall, though, it's the only product I could find in these dimensions ANYWHERE, so you take what you can get.