Proximity fobs
Proximity fobs, also known as proximity tokens, are small electronic devices that allow for keyless entry into a system used in access control. They communicate wireless signals that are received by a sensor to allow predetermined commands such as lock and unlock to occur based on presence. Proximity fobs are part of the contactless card technologies and are used for access control, time and attendance, and other applications. They are available in various designs for operation in the UHF, HF, and NFC frequency bands. Proximity fobs typically have a read range of up to 50 cm (20 in), which is the main difference from contactless smartcards with a range of 2 to 10 cm (1 to 4 in).