Do they still make those hardware ramdisks?

I'm doing a bit of experimentation with my server at home. I have software RAID5 (mdadm) set up on it right now, and obviously writing is pretty weak. If they still make them, I'd like to get one and set it up as a write-cache for the array (if possible). I believe it would have to be a hardware ramdisk (vs. an SSD) so it's battery-backed.