It is safe to use the power bank case because it has multiple circuit protection. The power bank case adopts intelligent chip, which can bring you quick and stable charging. Made of plastic, the power bank case is durable and environmental-friendly to use. It is welding-free, which is easy and convenient to install. The length of the power bank case is 17.2cm ,width is 7.9cm and height is 2.3cm. The power bank case is suitable for most devices. Item Name: Power Bank Case Material: Plastic Battery: 8 x 18650 Output/Input Power: 5V-1A/2A(Max) Features: Welding-free, Detachable, Intelligent Chip Size Details: 17.2cm x 7.9cm x 2.3cm/6.77" x 3.11" x 0.91" (Approx.) Notes: Due to the light and the screen setting difference, the item's color may slightly differs from the pictures. Please allow slight dimension difference due to the manual measurement. Attention: 1, Batteries and other item shown in the picture are not included. 2, The use of old batteries is not recommended. 3, Before buying, confirm that the surface is intact and cannot be broken, and the voltage should be between 3.2V-4.2V. 4, The positive and negative poles of the battery should be put correctly or it will cause short-circuit. 5, Batteries with damaged outer skins cannot be used because if the exposed parts touch the springs, it will easily cause short circuit. The consequence will be the same as connecting the positive and negative poles reversely. 6, The pointed battery cannot be used because the length of the pointed one is longer than the flat one and the contact area of the positive pole of the pointed one is smaller than that of the flat one, which will cause the case that the cover cannot be closed. Package Includes: 1 x Power Bank Case(Others Not Included)