What is a Harrop supercharger?

Excuse me, could you please elaborate on what exactly a Harrop supercharger is? I'm quite intrigued by the concept and its potential applications in the world of automotive performance enhancement. As someone who is passionate about cars and their underlying mechanics, I'm particularly curious about how this type of supercharger differs from others on the market, its advantages, and any notable vehicles that have incorporated it for improved performance. Additionally, I'd appreciate any insights you might have on the maintenance requirements and long-term durability of a Harrop supercharger.