This is selectable BMS for 3s or 4s or 5s batteries as shown in this image.

The universal Lithium Battery Protection and Charging Board is the perfect solution for managing your 3S, 4S, or 5S battery pack. This BMS (Battery Management System) ensures the safe and efficient charging and discharging of your batteries, protecting them from overcharge, overdischarge, and short circuit. The compact and lightweight design makes it easy to install in your projects, and the built-in USB output allows for easy charging of your devices. Keep your batteries in top condition with this reliable and versatile BMS.