Here's image of the Eldorado-Reno $100 plaque (front & back) that was mentioned on the board a while ago.
Size is 80mm x 56mm. Hard to see, but serial number is stamped on lower border of each side.

As far as I know, it is still current and in play on a mini-baccarat table on the casino floor. This is the lowest denimination plaque currently in play at any Nevada casino.