Joel, In the old days if a token was the same size and weight any dollar machine would accept it. In the mid-eighties they came out with a devive called a coin compairator. A token from the casino was placed in this device and the electronics would cull and reject anything that was not identical. This eliminated the use of other casinos tokens and the use of slugs. Of course the scammers became more sofisticated and made better slugs. Since there are very few token machines left today, the scammers now concentrate on bill validators.