It seems you're searching for the A2135 519mAh Lithium Polymer (Li-Po) rechargeable battery, which is designed for the AirPods Pro 3. This battery is a smaller form factor compared to typical Li-ion batteries, offering compactness and high energy density suitable for earbuds like the AirPods.

For sourcing options, you may want to explore specialized electronic component suppliers or wholesale platforms. Additionally, make sure to check if the battery is officially recommended or approved for your specific model to ensure compatibility and safety.

Let me know if you want more info on finding suppliers or any technical details about the battery!