A holder for 18650 cells solves the problem of connecting them in many electronic projects (eliminates the need to weld into a package or solder cells). The holder has metal contacts and wires with removed insulation at their ends, which ensure a secure connection between the battery and the target device.
Attention! Due to thicker positive wire (red), which protrudes beyond the hook, some batteries may not have a contact. This problem can be solved, among others, by adding a little bit of tin or use of a metal washer.