The "BE SURE Guarantee" offered by Royal Blinds is a service that provides additional assurance for customers when purchasing blinds or shutters. Here's a breakdown of what it entails:

1. **Additional Cost**: This guarantee comes with an extra charge, amounting to 10% of the cost of each blind or shutter purchased.

2. **Coverage for Measuring Errors**: The key benefit of this guarantee is its coverage for any measuring mistakes made by the customer. Measuring for blinds and shutters can be tricky, and errors can lead to products that don't fit properly.

3. **Remedy for Errors**: If a customer, under this guarantee, finds that their blinds or shutters don't fit due to a measuring error on their part, Royal Blinds offers two options:
   - **Re-cutting**: The incorrect blind or shutter will be re-cut to the correct dimensions.
   - **Replacement**: Alternatively, a completely new product can be sent out to replace the incorrectly measured one.

4. **Peace of Mind**: This guarantee essentially provides peace of mind, ensuring that customers won't have to bear the full cost of a new product if they make a measuring mistake.

5. **Encouragement for Self-Measurement**: By offering this guarantee, Royal Blinds encourages customers to measure their windows themselves, knowing that they have a safety net in case of errors.

The "BE SURE Guarantee" is a way for customers to safeguard their purchase against self-measurement errors, with an added cost for this extra security.