This is an MYLAPS Personal RC4 Hybrid Transponder Holder, and is intended for use with the MYLAPS RC4 transponder. This holder allows you to easily use your RC4 transponder in multiple cars. Simply remove the RC4 transponder from the holder in one vehicle, and unplug it from the receiver. Then plug the transponder into the receiver of another vehicle and install the transponder into the holder. This process allows you to easily swap out your transponder without the use of tools.