Power Stack is ultra-thin and lightweight stackable power bank. It uses tethered flexible Micro USB or lightning power cord. It is designed for providing emergency power to refill the smartphone or iOS devices. Each Power Stack can stack on the others, then to recharge all together. It is very helpful for many people usage. Drop the empty one to recharge, and get the charged one to use. Power Stack implements the magnetic alignment design for secure power contact. It allows one hand operation. It has a wonderful power bank design for family, office and multi-people's daily use.