Lol, the weight that bolts onto the flywheel. I bought a new Fidanza Alumn flywheel since I needed the 28oz for my 347 and decided to weight the 2 different weights that actually bolt on. My old Hawks Racing Alumn flywheel is almost an exact copy of the Fidanza. The 50oz weight is all I have for the Hawks since the 28oz was prob lost years ago during a move. The 50oz weight was almost the same weight, just a little less on the Hawks.