The B2Q74100 is the model number for the 3850mAh mobile phone battery used in the HTC Desire 19s. This battery is a Li-ion (Lithium-ion) type, providing the necessary power for the device. If you're looking for a replacement, you would need to ensure the battery is an OEM or high-quality third-party option to maintain performance and compatibility with the phone.

If you're looking to purchase or get more details on this battery, you may want to check with authorized HTC service providers or third-party mobile accessory retailers that specialize in batteries for older models like the HTC Desire 19s.