A friend of mine went to South America recently. He prudently went to a Boulder store to get a power connector adapter – and was promptly given the wrong thing by an ill-informed shopkeeper. So, upon reaching his destination, he ended up having to buy something that would work. Here’s photos of the adapters he needed:
These cost around $5 USD… the one’s recommended in Boulder – I think he said around $20. He took the bogus ones back and asked for a refund.
Double-check before you buy!