Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:

Create a detailed description for the following product: Hang-on, belonging to category: Ballpoint Pen

### Response:
By a hook on the top of the ballpoint pen, the Hang-on can be flexibly attached to backpacks or shoulder bags. By pushing a button on the side of the pen, a special mechanism allows users to unlock the hook as well as refill the lead. With a slight push of this button, the refill is retracted and locked again. The beautiful and simple design is based on the observation of user behaviour.
### End