Identify the unfair aspect with respect to the sentence extracted from an online Terms of Service:
```
any delivery dates or times provided by us ( or a courier ) are estimates only and are not guaranteed . 

```
. OPTIONS: ['Limitation of liability' 'Arbitration' 'Jurisdiction' 'Content removal'
 'Unilateral termination' 'Unilateral change' 'Contract by using'
 'Choice of law' 'None'].