Join Date: Jan 2012
Location: dark side of the moon
Your question has been answered what it is, as for cleaning bits like that, I put them in the dishwasher with jet dry. Honestly! Colgate toothpaste and a toothbrush works too, but more work. For the joints in the D ring pieces, get the waxed dental floss picks, it will lift gunk out and smooth it out so it doesn't creak when your horse mouths the bit.
I'll buy up the dirty/crappy looking ones from tack swaps, clean and shine them and then sell them at the next one for more $. I am a bit ho and hate to see nice bits go to waste :)