Amazon.com: HQRP Transmitter and Two Batteries Compatible with Citroen C2 C3 C4 C5 C6 C8 Key-Fob Remote Shell Case Cover Smart Key FOB : Automotive
Car Key Fob Battery For Citroen Flip Key C2 C3 C4 C5 C6 C8 Fast P&P 1 X CR1620 5000394030367 | eBay
How to replace / change key fob battery on BMW X2, X3, X4, X5, X6
Citroen DIY Repair Kit - Replacement 3 Button Remote Car Key Fob Case With VAN Symbol HU83 Flip Blade Micro Switches And CR1620 Battery | Remote Key Fobs