Mobile Fidelity Super HeavyWeight
Crutchfield Customer Review (What's this?)
Looks great, and makes a noticeable difference in slight warps. May not be necessary on higher end turntables that are already well dampened or quiet, but does help a significant amount on more modest decks. If you are already happy with a preamp and stylus, this is a logical next step, but get those other things right first.
Pros: Appearance, build quality