All transponders are available in read only (R/O and read write (R/W) types. Read Write types have 80-bits of re-programmable user memory.
Glass transponders are hermetically sealed which makes them completely water proof (e.g. for marine life), mount on metal tags are designed to perform better mounted on any metallic surface (e.g. vehicles).
The main benefit of the technology is the simplicity of the components and that it is very robust and easy to install.
Transponders are factory programmed during production by Texas Instruments with a 64-bit code which is virtually tamper proof plus an additional 16-bit CRC (error checking algorithm) to make sure that the tag is authentic and is an actual Texas Instruments tag.
The 64-bit code is a 16-digit hexadecimal number allowing up to 16 16 = 1.844x10 19 combinations of code, which is a very high number of combinations. This code is used as the unique identification (ID number).
Some transponders also have the following options available:
*Multi-page Transponder (MPT): same as read write transponder but with memory size of 1360 bits, organised into 17 pages with each page have 80bits of memory.
* Selective Addressable Multi-page Transponder (SAMPT): Same as the MPT function but enhanced to allow a user to read or program a single transponder in a group of transponders.
* Digital Signal Transponder (DST): Features a challenge/response encryption method that allows for secure authentication. Other features include secure id and optional password protection.