A transponder is simply the whole electronic device encapsulated in biocompatible glass. The size of the RoFo Tech transponders are Regular 2.12mm x 11.5mm, Mini 1.4mm x 8mm, and the smallest 1.25mm x 7 mm, both fall under the category of a ‘micro-transponder’. They can be referred to by many names including microchips, chips, PIT tags, transponders and RFID devices.