Metal Colour Casing
Key, Controller, Charging Socket Space
Ventilation Space
Max 16cells of 32700 can contain or 8x2
Max 42cells of 18650 can contain or 14x3
 
This is Lithium ion or lithium Phosphet battery box. Its cycle battery box. You can use this box in your electrical cycle. This case also have space for key and charging socket. Special two mounting system are there to attach the box in the cycle rod. This box compatible with only men's cycle. In female cycle it can be difficult to attach. Now which battery you can attach in this case
Very simple asnwer is 
- 8x2 Lithium Phosphet battery size max or 16 cells 32700
- 14x3 Lithium Ion Battery size or 42 cells 18650
There is special spacer for ventilation and wires. Space for Key and Controller (24v or 36v) and charging socket.