Hollow spy coins have been around since the days of the Cold War. Now you can secretly carry troves of important data with these Covert Coins. Available in US Quarter and .50 Euro denominations, they're hand-machined from real coins to create an interior compartment that's just the right size for a microSD card. Once closed, they're indistinguishable from regular currency and can't be opened without the included opening device, letting you carry them with regular change for added security.