Steve - The inserts are "extra" original NOS inserts that arrived with the NIB Bally's from the 70's and early 80's. They are all USA inserts. I do have some AUS inserts that I'm keeping for future machines destined for my gamesroom.

Classicplayfields sell the inserts. For some reason I cannot find them on their store. They had a great selection.

PBR have NOS - http://www.pbresource.com/CoinDoor.html