Biometric reader technology utilises the unique physiological characteristics of individuals such as retinal information, palm prints or fingerprints and these are compared to pre-stored data in order to provide accurate matching and identification of the authorised person before releasing the controlled door.  This is often considered the highest form of access security with the true uniqueness of each individual and the reduced likelihood of losing keys, cards or fobs.  Biometric solutions were historically deployed high-end applications although modern technology has now brought this to the fore in affordability.