The SRAM eTap Battery is the power source for the eTap and AXS systems. The same battery is interchangeable between front and rear derailleurs.
SRAM Red AXS eTap Braze-On Front Derailleur
battery - Does anyone make dummy batteries for eTap AXS derailleurs? - Bicycles Stack Exchange
SRAM EP AXS BATTERY (1PCS) - Kú Cycle
SRAM Rival eTap AXS Rear Derailleur 12-Speed 36t Max Medium Cage NO BATTERY
The SRAM eTap Battery is a power source for the eTap system. The same power unit is interchangeable between front and rear derailleurs.Provides up to 1000 kilometers of riding per charge.
SRAM AXS eTap Battery
ETAP BATTERY QUANTITY: 1, SRAM eTap Battery Front Or Rear Derailleur Quantity: 1 - Mornington & Berwick Cycles
SRAM RED eTap AXS Electronic 2x12-Speed Road Groupset - HRD Brake/Shif – Sierra Bicycle Supply
SRAM Red AXS XX / XX SL Mullet Transmission T-Type Groupset - Red eTap - Pro Bike Supply
For SRAM Battery Blocks Front/Rear Derailleur Etap Eagle AXS Dropper Post Cover Battery Protection Buckle - AliExpress
SRAM AXS Force 2020 - bucky rides
battery - Does anyone make dummy batteries for eTap AXS derailleurs? - Bicycles Stack Exchange