The replacement battery pack for your Norcon TTU-1D-X-L communicator is generally referenced as **TTU-BATT**. Because internal components, including battery chemistry (Lithium-Ion vs. older Ni-Cad versions), can vary based on your unit's manufacturing date, I strongly recommend verifying compatibility with the manufacturer using your serial number (100325). You can contact Norcon directly at (516) 239-0300 or via email at talk-thru@norconcomm.com.