This is the RMC/Rydon revolver nipple wrench mentioned by chaz12:
http://www.rmcoxyoke.com/inc/sdetail...rench/6549/236
I will vouch that this is good stuff, I got mine from the Buffalo Arms Co. along with good pricing on some other great stuff.
The wrench is hardened which makes it fairly impervious to the often experienced nipple wrench problems that the non-hardened wrenches suffer from.