Interesting factoid: Apparently Brunei Ringets are interchangeable with Singapore Dollars. I received a $10 Brunei Ringet as change recently and didn't even notice it because it looked like one of the special edition Singapore dollars. When I found it I started to get miffed thinking someone had passed me a bill of less value, but turns out it's usable/interchangeable here. I'm not sure how that works with the federal banks of both nations, but it's obviously not a problem.