There is a lot of great discussion on adjusters
here.
While I'm here, I'll offer this. I think aluminum adjusters that are installed properly (meticulously) are the best. I try and install mine with as much contact, wood to metal, as possible. The bridge's job is to transfer vibrations to the body of the bass with as little interference as possible. Metal transfers vibrations better than wood does, but it's not enough metal to make your bass sound like a tin can.
I also don't buy bridges with adjusters pre-installed. They are a real pain in the arse to fit properly. Is this a DIY project or are you taking your blank to a luthier? If your luthier is doing the fitting, save him/her some headache and buy the blank and adjusters separately..
