Covert Stealth Cameras: Stealth camera can be otherwise known as spy camera, spy cam, hidden surveillance, hidden cameras, nanny cams, nanny cameras, discreet cameras, covert cams. These digital video and audio recorders have their self recording storage built into them and some of them use different external standard SD Card, Micro SD Card, and Mini Memory card of different sizes such as 2GB Card, 4GB, 8GB, 16GB, and 32GB SD Card.