Jeff:

Called "mylar flips". If you do use them for chip storage/display be sure to buy the "Non-PVC" flips. PVC has a tendency to cause colors to run and a non-removable black stain (kind of like a mold stain) to develop at the top of the chip edge where the flip folds in some cheaply produced chips. I have had the stain develop on several of my "cheaply manufactured" Paul-son chips ($1 and under). There must have been a less expensive production process for casinos that were pinching pennies when they ordered chips.