For most electronic products, usually you can find the Product Name, Model No., Batch/Lot No. from the silkscreen at the bottom of the device, on the right / left / back side of the device, or at the inside of the device. For example:
1. Bluetooth Headphones:
The lot/batch No. of all wired earbuds is located on the sticker near the 3.5mm jack.
2. Bluetooth Adapters:
3. Bluetooth Speakers:
4. Bluetooth Car-kit: