Only for people who are familiar with battery performance and have practical experience in battery assembly. The PCB protection board with voltage detection to prevent overcharge and over discharge, safe to use. Help to repair and assemble battery pack. Due to different batches, there may be differences in product appearance, color, and printed text, which not affect the use. Colour:Random Color(Color is random, no specification is accepted) Material:PCB Package Contents: 2 x Circuit Board Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.