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: BTL-4000 SMART & PREMIUM, belonging to category: Modular Device Series

### Response:
BTL-4000 Smart and BTL-4000 Premium belong to a modular device series that has been developed especially for ultrasound, electrotherapy and laser therapy. Areas of application are, for example, muscle stimulation or pain reduction. Both systems are based on an advanced ultrasound technology, the so-called rotary field system. Such precise control makes the ultrasound therapy exceptionally effective and safe, for instance with regard to heat generation.
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