Device encryption is the best method to secure employee personal mobile devices as it protects the data on the device by converting it into unreadable code that cannot be easily deciphered by unauthorized people. Even if the device is lost or stolen, encrypted data remains protected. Remote wipes are also a secure method, but they are reactive and only come into play after a security incident has occurred. Locator applications may help find a lost device, but they don't protect the data on it. Screen locks are a basic security feature that provides the first line of defense against unauthorized access but are not as strong as encryption for protecting data.