Fine workmanship and durable. For the rechargeable (generally refers to the lithium battery) from the protection of the integrated circuit board. Lithium battery (rechargeable type) so need protection. As the lithium battery itself determines the material itself can not be overcharge, over discharge, overcurrent, short circuit and ultra-high temperature charge and discharge, so lithium battery will always follow a protective resistor with a sampling resistor and a current fuse.