Clocks: "Silver" Dice

Two extra dice, silver plated, limited to 200 sets, with the following rules:
"Yellow dice increase the tension in the auction: You can replace the yellow dice with the metal-plated dice and add both of the yellow dice to the bag at the beginning of the game.
This is only recommended with 3 or 4 players.
When a yellow die is pulled out of the bag, it is immediately removed from the game.
Therfore, for each yellow die pulled from the bag, there will be one less group of dice created for that particular auction (and two groups fewer if the two yellow dice come out at the same time).

There also are sets of 2 "Copper" dice, limited to 300, and sets of "Aluminum", limited to 400.