Lammers, at least from my experience, are used on just about every roulette table in casinos. The number on the lammer represents the dollar value of one 20 chip stack of roulette chips, and they are placed on top of a single roulette chip (a specific color) on the outside of the wheel. A 5 would mean the chips of that color have a cash value of 25 cents each. A 20 would mean the chips of that color have a cash value of $1 each. A 100 would mean the chips of that color have a cash value of $5 each. Since the player can declare the value of their chips when they buy in, the dealers need to know those values. It's pretty important...I've played a lot of $5/chip roulette on $1 minimum tables. If I buy in for $500 for 100 chips, when I color up and cash out, the dealer (could be someone who wasn't at the table when I bought in) must know the cash value of my chips.