It's a clamp, not really a weight. The VPI spindle has a little thread on the tip and this thing screws onto it. You can dial in the amount of force you wish by how hard you twist. Mike at VPI once told me just enough to touch the label and then maybe a quarter turn more rather than cranking the heck out of it.
I don't think it would be good for just any TT, pretty much a VPI item only.
Oops...free bump!
Paul