I've never been completely happy with my Fostex T50RPs- the original earpads were uncomfortably thin and were held in place with little squares of some kind of double-sided adhesive that softened in hot conditions. Because the factory pads fit really tightly, that would lead to them pulling free of the earpieces leaving sticky goo all over.
When the shiny coating on the factory pads began to flake off I considered just junking the headphones since I didn't want to replace the original pads with the same type and I was skeptical that anybody other than Fostex made replacements. When I saw the Brainwavz pads I was skeptical since they claimed to fit several models of headphone, but because the price was reasonable, I figured worst case I could use them on one of my other pairs.
I needn't have worried- not only do they fit perfectly, they're also way more comfortable than the originals, and the extra depth is a huge improvement. You'll need to be patient getting them on and I would recommend removing the factory adhesive (I used some alcohol wipes) to make it easier. The skirt portion of these pads covers more of the earpieces than the factory pads so they don't need any adhesive to stay in place, but they look like factory parts to me. I wish I'd known about them sooner.