$SMME ease of use of the SmartMetric biometric card along with the fact that it is powered by the SmartMetric internal green battery prior to the card being inserted into a reader to power the internal processor doing the fingerprint scan, means the SmartMetric biometric card is the only card that can work across all card reader types and situations. Biometric cards that do not have an internal independent power supply are very limited on where such cards can be used.