Bought two sets, one for my DT880s and one for my MMX 300s. I like them on my MMX 300s, less so on my DT880s. Just know that your headphones will sound different.
These are very comfortable--as comfortable as the stock DT880 earpads and much more comfortable than the MMX 300 earpads. The cooling foam is a neat effect which IMO puts them a step above the DT880 earpads in terms of comfort.
However, they changed the sound quality more than I expected. Sound quality is pretty subjective, but they ...