The Opto 22 G4BATT32 provides a convenient solution for replacing discharged memory retention batteries in G4 and M4 controllers. This kit includes a 3.6V lithium battery, a keyed connector for solderless replacement, and Velcro mounting for easy user installation. The battery boasts a long shelf life due to its low self-discharge rate, ensuring it's ready when needed. Replacing the battery will erase the controller's strategy and persistent data, requiring a re-download after installation.