This is a power bank case is made of 3D Printed. Its of 2usb type B power bank circuit with Type B charger slot, and 2pcs USB discharge cable. Its a DIY kit, you need to make the power bank itself. Battery is not provided with it. It does not have any spring system. You can fit max 4cells of 18650 lithium ion 3.7volt can be attached with it. To fit the battery cells either you have to solder or spot the battery cells. We do not provide cells with this case. 
 
Package Inlcude -
1 x power bank case
1 x circuit