I just purchased two saddles, so that I can have a backup is I mess the first one, as they need to be thoroughly adjusted to fit.
Both of them have the exact same dimensions, they are made out of very good quality bone. What's interesting, though, is that, when held under powerful light, one is almost translucent, while the other is visibly more dense. It is an organic material, so I get it.
It will be a fun DIY project - I already have a bone saddle on my acoustic, but it is a little bit loose, so I will eventually replace it with one of these.
Later Edit - very easy to work with. I have managed to hand shape a beatiful saddle, with a perfect, snug fit in the slot.