Currency Fluctuation + Foreign Interest rate?

Any experts out there who can tell me what the currency ( any foreign currency) + Foreign Interest rate ( of that same currency ) would equal as a product? What would you call this kind of investment?

Public Comments

1. The product of the variation of the foreign currency and the foreign interest rate would be the ROI (return on investment).
2. I would simply call that a foreign currency deposit. Lots of people do it especially in low interest rate countries like Japan. Be very careful of foreign exchange rate risk. There's no such thing as a free lunch.
3. Interest Rate Parity Theorem?