This is not the first time I buy and use "decouplers" for my amps/cabs.
For the price (and this is really cheap one, trust me on that) it does a good job stopping the low frequencies "leakage" to the floor, the rest of the apartment, the building etc, it looks great and it seems like it's gonna last for a long time.
It can accommodate an 1x12" cab (in my case, a Marshall 1912) with no issues whatsoever and I bet it will perfect even with an oversized 1x12".
Again, this product is at least half the price some very well known ones have and it does a good job.