You've probably already found a few new things you can use to promote your business. Write a paragraph of around 20-50 words, the fewer the better, that uses the best differences and benefits from your research. Communicate without any hype who you are, what you do, why you're different and how you can benefit your prospects and customers. The 25 years is the hidden proof of your experience. Finally - when creating your USP, you want to remember emotion.
Most people justify their purchase with logic, but they make the purchase with emotion.
They want to do business with you because you make them feel smart, or good about the decision or whatever. They need logical facts to back up the emotional decision they made. Don't lose sight of this, it's very important. Your USP should state the biggest benefit and most unique benefit your prospects will get from doing business with you. Keep it short.