Bell inequalities are an important tool in device-independent quantum information processing because their violation can serve as a certificate of relevant quantum properties. Probably the best known example of a Bell inequality is due to Clauser. Horne. Shimony and Holt (CHSH). https://www.diegojavierfares.com/top-deal-Spitfire-Sapphires-90d-Skateboard-Wheels-58mm-p18591-great-pick/