The old style TranX 260 and TranX 160 Transponders can be identified by the flat front, the hook at the bottom of the transponder, and the loop at the top of the transponder. These units were manufactured until 2005.
The current version has a rounded front, a recess in the bottom, and a hole through the top. This style uses the TranX 160 / 260 Battery Charger for New-Style Transponders, Part No. 5013.