Warburton Special Optimum Pressure System - Special OPSWarburton Special O. P. S Optimal Pressure System There's no such thing as "no pressure" when it comes to playing the trumpet. However, too much pressure is a familiar problem with most players at some point in their playing career. The specially designed Optimal Pressure System fits right into your trumpet and works with your normal mouthpiece top to teach you to use less pressure while actually playing!